Multi-power source locomotive control method and system

ABSTRACT

Control modes for operating multiple power sources include energy storage systems and applicable to large systems such as locomotives. Selectable operating modes are provided for different locomotive speed ranges and work loads. A common DC bus electrical architecture is used so that prime power sources need not be synchronized. Multiple-engine locomotives have the engine systems that may be electrically connected in parallel or in series or in combinations of parallel and series to a DC bus.

This application is a continuation of U.S. patent application Ser. No.12/019,464, filed Jan. 24, 2008, now U.S. Pat. No. 7,677,347 whichclaims the benefit of U.S. Provisional Patent Application Ser. No.60/886,465 filed Jan. 24, 2007, the entirety of the foregoingapplications are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to means of applying variouscontrol options for various control modes for a vehicle comprising aplurality of power sources and particularly to (1) a locomotive having aplurality of engines and (2) a locomotive having a plurality of enginesand an energy storage system. The general method can be applied to alocomotive having a plurality of power sources, fuel types and drivetrain combinations. These methods pertain to multiple engineconfigurations where the engines may be connected in parallel to acommon DC bus or in series to a common DC bus or in combinations ofparallel and series to a common DC bus.

BACKGROUND OF THE INVENTION

Railroads are under increasing pressure to reduce emissions and toincrease fuel efficiency. One of several responses to these forces hasbeen the development of hybrid locomotives. Donnelly has disclosed theuse of a battery-dominant hybrid locomotive in U.S. Pat. No. 6,308,639which is incorporated herein by reference. Hybrid locomotives can reduceemissions and fuel consumption in rail operations such as yard switchingbut they are less effective for medium haul freight or commuter trains.

In U.S. patent issued Dec. 4, 2007 entitled “Locomotive Power TrainArchitecture”, Donnelly et al. have further disclosed a generalelectrical architecture for locomotives based on plurality of powersources, fuel and drive train combinations. The power sources may be anycombination of engines, fuel cells, energy storage and regenerativebraking. This application is also incorporated herein by reference.

The development of multi-engine locomotives is another response to thesearch for more energy efficient and emissions compliant locomotives. InU.S. patent application Ser. No. 11/201,267 filed Aug. 9, 2005 entitled“Multiple Engine Locomotive Configuration”, Donnelly et al. havedisclosed a means of packaging engine modules on a multi-enginelocomotive that optimizes the power density of the locomotive powerplants while reducing emissions and fuel consumption. In a U.S. patentapplication Ser. No. 11/412,071 filed Apr. 25, 2006 entitled “MultiplePrime Power Source Locomotive Control”, Donnelly et al. further disclosea general means for controlling and balancing a number of prime powersources powering a locomotive, including control for various operatingmodes such as for example, (1) a maximum fuel efficiency mode; (2) aminimum emissions mode (whether of a substance or energy, such asnoise); (3) a combination mode of good fuel efficiency and lowemissions; (4) a maximum power mode; and (5) an optimum engine lifetimemode.

In a U.S. Provisional Patent Application 60/814,595 entitled“Multi-Power Source Locomotive Control Modes” by Donnelly filed Jun. 15,2006, methods of overriding preset multi-engine selection algorithmswere disclosed. These methods overcome deficiencies of preset engineselection algorithms that occur in certain common railroad situations.

In U.S. Provisional Patent Application entitled “Marine Power TrainArchitecture” by Donnelly and Watson filed Oct. 24, 2006, a multi-enginearchitecture was disclosed in which the engine system outputs wereconnected electrically in series across a DC bus. In this provisional,so-called soft hybrid architectures were also disclosed.

There are a number of practical considerations that need to beconsidered in implementing control schemes for multi-power sourcelocomotives. For example, if diesel engines are used, strategies must bedeveloped to ensure the engines are not turned on and off toofrequently. As another example, maximum tractive effort may be requiredin low speed yard switching work; maximum fuel economy may be requiredin short haul medium speed operations; maximum acceleration and maximumfuel economy may be required at different times in commuter operation;and various combinations of maximum fuel economy and minimum emissionsmay be required in different locations on long haul routes. Thesevarious operating modes cannot all be accommodated by a single notchpower table prescription for selecting the number of engines, enginespeeds and engine power levels. Thus there is a need for a practicalmethod of selecting engine operating modes by the locomotive engineerthat allows the performance benefits of a multi-engine locomotive to berealized.

Further, means for controlling and balancing a number of prime powersources powering a locomotive, including control for various operatingmodes; and methods of overriding preset multi-engine selectionalgorithms need to be extended to cover multi-engine configurationswhere the engines are connected electrically in series or in parallel ora combination thereof.

SUMMARY OF THE INVENTION

These and other needs are addressed by the various embodiments andconfigurations of the present invention which are directed generally tocontrolling the individual prime power systems of a multi-prime powersource vehicular propulsion system. The inventions disclosed herein areapplicable to locomotives utilizing prime power sources such as dieselengines, gas turbine engines, fuel cells, other types of internalcombustion engines or combinations of these. The inventions disclosedherein are also applicable to locomotives utilizing multiple prime powersources and energy storage units (hybrid locomotives). The inventionsmay also apply to other types of vehicles or systems that requiresubstantial power and low emissions utilizing multiple power plantcombinations. Examples of other vehicles and systems include largetrucks such as mining trucks, tugboats and large mobile cranes.

More particularly, the present invention provides a method ofcontrolling a desired total system output power from a vehiclecomprising a plurality of power sources, the plurality of power sourcesoutputting DC electrical power to a common DC bus, and the vehicle alsocomprising a variable power control having a plurality of powersettings, the method comprising the steps of:

-   -   a) selecting a number of power sources to be used according to a        schedule to provide power to the DC common bus;    -   b) activating the power sources according to the schedule;    -   c) setting a desired range of a parameter indicative of power        available on the DC common bus from at least one of voltage or        current on the DC common bus;    -   d) measuring a signal corresponding to the parameter indicative        of power available on the DC common bus from at least one of        voltage or current on the DC common bus;    -   e) for each of the plurality of power sources, measuring a        signal indicative of a power source operational parameter from        said each of the plurality of power sources;    -   f) determining an output power for each of the plurality of        power sources, based on the measurement of the signal indicative        of the power source operational parameter from said each of the        plurality of power sources and the signal corresponding to the        parameter indicative of at least one of voltage or current on        the DC common bus; and    -   g) if the output power of one of the plurality of power sources        is different from a target output power, adjusting a power        source control parameter of said one of the plurality of power        sources to correct the difference.

The present invention also provides a system for controlling a desiredtotal system output power from a vehicle comprising a plurality of powersources, the plurality of power sources outputting DC electrical powerto a common DC bus, and the vehicle also comprising a variable powercontrol having a plurality of power settings, the control systemcomprising:

-   -   selecting means for selecting a number of power sources to be        used according to a schedule to provide power to the DC common        bus;    -   activating means for activating the power sources according to        the schedule;    -   setting means for setting a desired range of a parameter        indicative of power available on the DC common bus from at least        one of voltage or current on the DC common bus;    -   first measuring means for measuring a signal corresponding to        the parameter indicative of power available on the DC common bus        from at least one of voltage or current on the DC common bus;    -   second measuring means, for each of the plurality of power        sources, for measuring a signal indicative of a power source        operational parameter from said each of the plurality of power        sources;    -   determining means for determining an output power for each of        the plurality of power sources, based on the measurement of the        signal indicative of the power source operational parameter from        said each of the plurality of power sources and the signal        corresponding to the parameter indicative of at least one of        voltage or current on the DC common bus; and    -   adjusting means for adjusting a power source control parameter        of said one of the plurality of power sources to correct a        difference between the output power of one of the plurality of        power sources and a target output power.        Multi-Engine Locomotive Control

The present inventions include multi-engine locomotive configurationswhere the engine systems are connected (1) in parallel to a common DCbus; (2) in series with a common DC bus; or in combinations of paralleland series. The first two configurations require different strategies tomeasure individual engine system output power and to ensure that eachengine system is contributing the desired amount of power to the DC bus.

Parallel Connected Engine Systems

In parallel configuration, the output voltage of an engine systemproviding power to the DC bus is very close to the voltage measured onthe DC bus. If, for example, the output voltage of an engine system isjust below bus voltage then that engine system will not provide anypower to the DC bus. However, a measurement of the output current of anengine system is a sensitive direct measurement of the engine system'spower output and is the preferred method of determining engine systemoutput power. An engine system's output power is its output currenttimes the DC bus voltage. In parallel configuration, the general methodof ensuring the desired engine system output power is then:

-   -   set the desired DC bus voltage or bus voltage range and measure        the DC bus voltage;    -   for each engine system, measure its output current and use this        to determine its output power (engine system current times DC        bus voltage);    -   if the engine system is not outputting the desired power, adjust        an engine system electrical or mechanical parameter to produce        desired engine system output current and hence power        Series Connected Engine Systems

In series configuration, the output voltage of each engine systemproviding power to the DC bus is added to produce the voltage measuredon the DC bus. Thus a measurement of the output voltage of an enginesystem is an accurate measurement of the engine system's power to the DCbus and is the preferred method of determining the engine system'soutput power. An engine system's output power is its output voltagetimes the DC bus current. If only DC bus voltage is measured, an enginesystem's relative output power compared to the other engines providingpower can still be obtained by each engine system's measured outputvoltage. In series configuration, the general method of ensuring thedesired engine system output power is then:

-   -   set the desired DC bus voltage or bus voltage range and measure        the DC bus voltage; or set the desired DC bus current or bus        current range and measure the DC bus current    -   for each engine system, measure its output voltage and use this        to determine its output power (its voltage times DC bus current)        or output power relative to the other engines (relative output        voltages are relative output powers since current is the same)        if the engine system is not outputting the desired power or        desired power relative to the other engines, adjust an engine        system electrical or mechanical parameter to produce desired        engine system output voltage and hence power.        Soft-Hybrid Configurations

Another invention disclosed herein is a propulsion system for amulti-engine locomotive with multiple engines in parallel and a hybridauxiliary power system. The auxiliary power system can provide thelocomotives auxiliary power when one or more engines are operating orwhen no engines are operating. The auxiliary power system can also beused to start any of the multiple engines of the main propulsion system.An alternate propulsion system for a multi-engine locomotive withmultiple engines in parallel and a hybrid auxiliary power system isdisclosed. In this configuration, the main propulsion system is drivenby a mechanical transmission rather than by an electrical transmission.

These and other advantages will be apparent from the disclosure of theinvention(s) contained herein.

The above-described embodiments and configurations are neither completenor exhaustive. As will be appreciated, other embodiments of theinvention are possible utilizing, alone or in combination, one or moreof the features set forth above or described in detail below.

The following definitions are used herein:

A locomotive is generally a self-propelled railroad prime mover which ispowered either by a steam engine, diesel engine or externally such asfrom an overhead electrical catenary or an electrical third rail.

An engine refers to any device that uses energy to develop mechanicalpower, 10 such as motion in some other machine. Examples are dieselengines, gas turbine engines, microturbines, Stirling engines and sparkignition engines.

A prime power source or a prime mover refer to any device that usesenergy to develop mechanical or electrical power, such as motion in someother machine. Examples include but are not limited to diesel engines,gas turbine engines, microturbines, Stirling engines, spark ignitionengines or fuel cells.

A motor refers to a device that produces or imparts motion.

A traction motor is a motor used primarily for propulsion such ascommonly used in a locomotive. Examples are an AC or DC induction motor,a permanent magnet motor and a switched reluctance motor.

An energy storage system refers to any apparatus that acquires, storesand 20 distributes mechanical or electrical energy which is producedfrom another energy source such as a prime energy source, a regenerativebraking system, a third rail and a catenary and any external source ofelectrical energy. Examples are a battery pack, a bank of capacitors, acompressed air storage system and a bank of flywheels.

An electrical energy converter refers to an apparatus that transmits orblocks the flow of electrical energy and may also increase or reducevoltage and change the frequency of the transmitted energy includingchanging the frequency to zero. Examples are but are not limited to aninverter, a rectifier circuit, a chopper circuit, a controlled rectifiersuch as a cycle converter, a boost circuit, a buck circuit and abuck/boost circuit.

A mechanical-to-electrical energy conversion device refers an apparatusthat converts mechanical energy to electrical energy. Examples includebut are not limited to a synchronous alternator such as a wound rotoralternator or a permanent magnet machine, an asynchronous alternatorsuch as an induction alternator, a DC generator, and a switchedreluctance generator.

An engine system as used herein refers to the engine and itsmechanical-to electrical energy conversion device so the output power ofan engine system is electrical.

Dynamic braking is implemented when the electric propulsion motors areswitched to generator mode during braking to augment the braking force.The electrical energy generated is typically dissipated in a resistancegrid system.

Regenerative braking is the same as dynamic braking except theelectrical energy generated is recaptured and stored in an energystorage system for future use

Engine speed is the rotary speed of the engine output drive shaft and istypically expressed in rpms.

Alternator speed is the rotary speed of the alternator rotor and istypically expressed in rpms. The alternator speed is commonly the sameas engine speed since they are usually directly connected with nointermediate gearing.

An IGBT is Insulated Gate Bipolar Transistor which is a power switchingdevice capable of sequentially chopping a voltage waveform at a veryfast rate.

The duty cycle of an IGBT is the ratio of time that the IGBT is switchedon (conducting) to the total time that the IGBT is switched on(conducting) and off (nonconducting).

As used herein, “at least one”, “one or more”, and “and/or” areopen-ended expressions that are both conjunctive and disjunctive inoperation. For example, each of the expressions “at least one of A, Band C”, “at least one of A, B, or C”, “one or more of A, B, and C”, “oneor more of A, B, or C” and “A, B, and/or C” means A alone, B alone, Calone, A and B together, A and C together, B and C together, or A, B andC together.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages of the invention will becomeapparent upon reading the detailed description and upon referring to thedrawings in which:

FIG. 1 is an plot of engine power versus engine speed.

FIG. 2 is an plot of engine torque versus engine speed.

FIG. 3 is an example of a fuel map for a diesel engine.

FIG. 4 is an example of an emissions map for a diesel engine.

FIG. 5 is a plot of engine power versus engine speed for a single engineat a preferred condition.

FIG. 6 is a plot of total locomotive engine power versus notch settingfor a multi-engine locomotive configuration.

FIG. 7 is a plot of total locomotive engine power versus notch settingfor a hybrid multi-engine locomotive configuration.

FIG. 8 is a schematic of the principal propulsion components of alocomotive with multiple prime power sources in parallel.

FIG. 9 is an example of the overall electrical schematic of amulti-engine locomotive power system with multiple engines in parallel.

FIG. 10 is an overview flowchart showing the primary steps in amulti-engine control loop with multiple engines in parallel.

FIG. 11 is an example of a main flow chart of automated decision makingfor controlling the overall multi-engine selection process with multipleengines in parallel.

FIG. 12 is an example of a flow chart for selecting and configuringengines for any of the notch 1 to 8 power settings with no load controlwith multiple engines in parallel.

FIG. 13 is an example of a flow chart for selecting and configuringengines for any of the notch 1 to 8 power settings with load controlwith multiple engines in parallel.

FIG. 14 is an example of a flow chart for selecting and configuringengines for any of number of idle settings with multiple engines inparallel.

FIG. 15 is an example of a flow chart for selecting and configuringengines for dynamic braking with multiple engines in parallel.

FIG. 16 is an example of a flow chart for controlling enginedeactivation with multiple engines in parallel.

FIG. 17 is an example of a flow chart for activating an engine withmultiple engines in parallel.

FIG. 18 is another example of a main flow chart of automated decisionmaking for controlling the overall multi-engine selection process withmultiple engines in parallel.

FIG. 19 is a schematic of a multi-engine current-based control feedbacksystem with multiple engines in parallel.

FIG. 20 is a schematic of an alternate multi-engine current-basedcontrol feedback system with multiple engines in parallel.

FIG. 21 is a schematic circuit diagram of an alternate engine system fora multiengine locomotive.

FIG. 22 is a schematic block diagram of a propulsion system for amulti-engine locomotive with multiple engines in series.

FIG. 23 is a schematic circuit diagram of a propulsion system for amulti-engine locomotive with multiple engines in series.

FIG. 24 is an overview flowchart showing the primary steps in amulti-engine control loop with multiple engines in series.

FIG. 25 is an example of a main flow chart of automated decision makingfor controlling the overall multi-engine selection process with multipleengines in series.

FIG. 26 is an example of a flow chart for selecting and configuringengines for any of the notch 1 to 8 power settings with no load controlwith multiple engines in series.

FIG. 27 is an example of a flow chart for selecting and configuringengines for any of the notch 1 to 8 power settings with load controlwith multiple engines in series.

FIG. 28 is an example of a flow chart for selecting and configuringengines for any of number of idle settings with multiple engines inseries.

FIG. 29 is an example of a flow chart for selecting and configuringengines for dynamic braking with multiple engines in series.

FIG. 30 is an example of a flow chart for controlling enginedeactivation with multiple engines in series.

FIG. 31 is an example of a flow chart for activating an engine withmultiple engines in series.

FIG. 32 is another example of a main flow chart of automated decisionmaking for controlling the overall multi-engine selection process withmultiple engines in series.

FIG. 33 is a schematic of a multi-engine current-based control feedbacksystem with multiple engines in series.

FIG. 34 is a schematic of an alternate multi-engine current-basedcontrol feedback system with multiple engines in series.

FIG. 35 is a schematic block diagram of a propulsion system for amulti-engine locomotive with multiple engines in parallel and a hybridauxiliary power system.

FIG. 36 is a schematic circuit diagram for a multi-engine locomotivewith multiple engines in parallel and a hybrid auxiliary power system.

FIG. 37 is a schematic block diagram of an alternate propulsion systemfor a multi-engine locomotive with multiple engines in parallel and ahybrid auxiliary power system.

FIG. 38 is a schematic block diagram of yet another alternate propulsionsystem for a multi-engine locomotive with multiple engines in series anda hybrid auxiliary power system.

FIG. 39 is an example of total DC bus input amperes versus volts for athree engine locomotive where the engine systems are connectedelectrically in series.

FIG. 40 is an example of total locomotive tractive effort versus speedfor a three engine locomotive where the engines systems are connectedelectrically in series.

LIST OF TABLES

Table 1 is a table of the output brake horsepower (“BHP”) versus enginespeed (“rpm”) for a single engine.

Table 2 is a table of the output brake horsepower (“BHP”) versus enginespeed (“rpm”) for a multi-engine locomotive with fixed engine selection.

Table 3 is a table of the output brake horsepower (“BHP”) versus enginespeed (“rpm”) for a multi-engine locomotive with a single variableengine.

Table 4 is a table of the output brake horsepower (“BHP”) versus enginespeed (“rpm”) for a multi-engine locomotive with engine selectiondetermined by load.

Table 5 is a table of the output brake horsepower (“BHP”) versus enginespeed (“rpm”) for a multi-engine locomotive with a fixed number ofengines selected.

Table 6 is a table of the output brake horsepower (“BHP”) versus enginespeed (“rpm”) for a multi-engine locomotive with engines selected formaximum fuel economy.

Table 7 is a table of the output brake horsepower (“BHP”) versus enginespeed (“rpm”) for a multi-engine locomotive with engines selected forminimum emissions.

Table 8 is a table of the output brake horsepower (“BHP”) versus enginespeed (“rpm”) for a multi-engine hybrid locomotive.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As shown in the attached figures, according to the present invention,there is provided a method of controlling a desired total system outputpower from a vehicle comprising a plurality of power sources, theplurality of power sources outputting DC electrical power to a common DCbus, and the vehicle also comprising a variable power control having aplurality of power settings. A shown in FIG. 10, the method comprisesthe steps of:

-   -   a) selecting a number of power sources to be used according to a        schedule to provide power to the DC common bus; 1002    -   b) activating the power sources according to the schedule; 1003    -   c) setting a desired range of a parameter indicative of power        available on the DC common bus from at least one of voltage or        current on the DC common bus; 1004    -   d) measuring a signal corresponding to the parameter indicative        of power available on the DC common bus from at least one of        voltage or current on the DC common bus;    -   e) for each of the plurality of power sources, measuring a        signal indicative of a power source operational parameter from        each of the plurality of power sources;    -   f) determining an output power for each of the plurality of        power sources, based on the measurement of the signal indicative        of the power source operational parameter from each of the        plurality of power sources and the signal corresponding to the        parameter indicative of at least one of voltage or current on        the DC common bus; 1005 and    -   g) if the output power of one of the plurality of power sources        is different from a target output power, adjusting a power        source control parameter of one of the plurality of power        sources to correct the difference 1006, 1007.

Preferably, the power source operational parameter comprises at leastone of current, voltage, torque, speed and fuel injection rate.

According to one preferred embodiment of the present invention, theplurality of power sources are connected in parallel to the common DCbus, the parameter indicative of the power available on the DC commonbus is the DC common bus voltage, and the signal indicative of the powersource operational parameter is at least one of current, voltage,torque, speed and fuel injection rate from said each of the plurality ofpower sources.

According to another preferred embodiment of the present invention, theplurality of power sources are connected in series to the common DC bus,the parameter indicative of the power available on the DC common bus isthe DC common bus voltage, and the signal indicative of the power sourceoperational parameter is at least one of current, voltage, torque, speedand fuel injection rate from said each of the plurality of powersources.

According to another preferred embodiment of the present invention, theplurality of power sources are connected in series to the common DC bus,the parameter indicative of the power available on the DC common bus isthe DC common bus current, and the signal indicative of the power sourceoperational parameter is at least one of current, voltage, torque, speedand fuel injection rate from said each of the plurality of powersources.

Preferably, the vehicle may operate in a mode wherein all selected powersources in step a) operate at a same power level.

Preferably, the vehicle may operate in another mode, wherein allselected power sources but one in step a) operate at a same power level,the one power source operating at a different power level and enablingthe all selected power sources but one to optimize an operatingparameter.

Preferably, the above-mentioned operating parameter is selected from thegroup consisting of (i) fuel efficiency; (ii) low emissions; (iii) noiselevel; (iv) power; (v) tractive effort; (vi) engine lifetime, (vii)location of the vehicle and (viii) any combination thereof.

Preferably, the vehicle may operate in another mode, wherein each powersetting corresponds to a power level which is obtained by adding anotherpower source as soon as the currently operating power sources reach aselected percentage of their rated power.

Preferably, the vehicle may operate in another mode, wherein an operatorof the vehicle manually selects at least one of the number of powersources to be used according to the schedule and an operating parameterof one of the number of power sources to be used according to theschedule, said operating parameter being selected from the groupconsisting of (i) fuel efficiency; (ii) low emissions; (iii) noiselevel; (iv) power; (v) tractive effort; (vi) engine lifetime, (vii)location of the vehicle, (viii) maximum engine output power, (ix) enginespeed and (x) any combination thereof.

Preferably, the vehicle may operate in another mode, wherein said numberof power sources to be used and the power and engine speed setting foreach power source are selected in order to obtain a desired fuelefficiency for that power setting and are determined using a controllerprogrammed to use fuel consumption maps for each power source.

Preferably, the vehicle may function in another mode, wherein saidnumber of power sources to be used and the power and engine speedsetting for each power source in order to obtain the desired emissionsfor that power setting are determined using a controller programmed touse an emissions map for each power source.

Preferably, the plurality of power sources comprise a plurality of primemovers and one or more energy storage systems.

Preferably, the vehicle is of a type selected from the group consistingof locomotives, trucks, tugboats and cranes.

Preferably, the variable power control having a plurality of powersettings includes one or more idle settings and a plurality of powernotch settings.

Preferably, the vehicle may operate in another mode, wherein step a)comprises the steps of:

-   -   i) determining a specified output power for a selected notch        setting and vehicle speed;    -   ii) selecting an optimum power source operating mode;    -   iii) selecting a number of power sources required to provide the        specified output power for the selected notch setting and        vehicle speed;    -   iv) selecting specific power sources to provide the specified        output power for the selected notch setting and vehicle speed;    -   v) verifying whether any of the selected specific power sources        need to be derated;    -   vi) if a power source from any of the selected specific power        sources needs to be derated, derating said power source needing        derating and returning to step iii); and    -   vii) if a power source from the plurality of power sources is        not required to provide the specified output power for the        selected notch setting and vehicle speed, deactivating said        non-required power source;

Preferably, the vehicle may operate in dynamic braking mode and themethod further comprises, prior to step a), the steps of:

-   -   aa) selecting a dynamic braking power level;    -   bb) determining if dynamic braking available power is sufficient        for providing the desired total system output power;    -   cc) if the dynamic braking available power is sufficient for        providing the desired total system output power, performing        step g) wherein the desired total system output power comprises        output power from dynamic braking; and    -   dd) if the dynamic braking available power is not sufficient for        providing the desired total system output power, performing        step a) wherein the desired total system output power comprises        output power from dynamic braking and output power from the        plurality of power sources.

Preferably, the method further comprises a step of deactivating aselected one of the plurality of power sources, the deactivating stepcomprising the steps of:

-   -   I) selecting between an idle mode and a shutdown mode;    -   II) if the idle mode is selected, performing the steps of:        -   A. selecting between a high idle power level and a low idle            power level;        -   B. setting an excitation current for the selected            deactivating power source such that an output voltage of the            selected deactivating power source is below a DC common bus            voltage        -   C. selecting an optimum operating mode for the selected            deactivating power source; and        -   D. adjusting the excitation current for the selected            deactivating power source such that the output voltage of            the selected deactivating power source is below a DC common            bus voltage and the selected deactivating power source            achieves said optimum operating mode; and    -   III) if the shutdown mode is selected, performing the steps of:        -   E. from look-ahead data, determining if the power source can            be turned off;        -   F. if a time required to shutdown the power source is below            a threshold, performing steps II) A through II) D; and        -   G. if the time required to shutdown the power source is            above the threshold, turning off the engine.

Preferably, for activating the power sources, step b) comprises thesteps of:

-   -   I) if the power sources are off, preheating the power sources;    -   II) turning on lubricating oil flow;    -   III) starting the power sources;    -   IV) selecting between a high idle power level and a low idle        power level;    -   V) setting an excitation current for the selected activating        power source such that an output voltage of the selected        activating power source is below a DC common bus voltage    -   VI) selecting an optimum operating mode for the selected        activating power source; and    -   VII) adjusting the excitation current for the selected        activating power source such that the output voltage of the        selected deactivating power source is below a DC common bus        voltage and the selected activating power source achieves said        optimum operating mode.

According to the present invention, there is also provided a system forcontrolling a desired total system output power from a vehiclecomprising a plurality of power sources, the plurality of power sourcesoutputting DC electrical power to a common DC bus, and the vehicle alsocomprising a variable power control having a plurality of powersettings, the control system comprising:

-   -   selecting means for selecting a number of power sources to be        used according to a schedule to provide power to the DC common        bus;    -   activating means for activating the power sources according to        the schedule;    -   setting means for setting a desired range of a parameter        indicative of power available on the DC common bus from at least        one of voltage or current on the DC common bus;    -   first measuring means for measuring a signal corresponding to        the parameter indicative of power available on the DC common bus        from at least one of voltage or current on the DC common bus;    -   second measuring means, for each of the plurality of power        sources, for measuring a signal indicative of a power source        operational parameter from each of the plurality of power        sources;    -   determining means for determining an output power for each of        the plurality of power sources, based on the measurement of the        signal indicative of the power source operational parameter from        each of the plurality of power sources and the signal        corresponding to the parameter indicative of at least one of        voltage or current on the DC common bus; and    -   adjusting means for adjusting a power source control parameter        of one of the plurality of power sources to correct a difference        between the output power of one of the plurality of power        sources and a target output power.

Preferably, the power source operational parameter comprises at leastone of current, voltage, torque, speed and fuel injection rate.

According to a preferred embodiment of the invention, the plurality ofpower sources are connected in parallel to the common DC bus, theparameter indicative of the power available on the DC common bus is theDC common bus voltage, and the signal indicative of the power sourceoperational parameter is at least one of current, voltage, torque, speedand fuel injection rate from each of the plurality of power sources.

According to another preferred embodiment of the invention, theplurality of power sources are connected in series to the common DC bus,the parameter indicative of the power available on the DC common bus isthe DC common bus voltage, and the signal indicative of the power sourceoperational parameter is at least one of current, voltage, torque, speedand fuel injection rate from said each of the plurality of powersources.

According to another preferred embodiment of the invention, theplurality of power sources are connected in series to the common DC bus,the parameter indicative of the power available on the DC common bus isthe DC common bus current, and the signal indicative of the power sourceoperational parameter is at least one of current, voltage, torque, speedand fuel injection rate from said each of the plurality of powersources.

According to another preferred embodiment of the invention, the systemfurther comprises an energy storage system and an auxiliary power systemconnected to the DC common bus and wherein each of the plurality ofpower sources comprises an output shaft connected to a mechanicaltransmission driving a plurality of traction motor propulsion systems.

According to another preferred embodiment of the invention, the vehiclefurther comprises an auxiliary power system bus connected to theplurality of power sources, an energy storage system connected to theauxiliary power system bus; and an auxiliary power system connected tothe auxiliary power system bus.

The selecting means, activating means, setting means, determining means,adjusting means, first and second measurement means mentioned aboveinclude any electronic device, computer, programmable logic controller,circuit, control system or other similar systems that can perform suchfunctions

Engine Operating Modes

The following examples of control modes are based on a hypotheticallocomotive having six identical engines, each engine having a powerversus rpm and a torque versus rpm curves qualitatively such as a shownin FIGS. 1 and 2.

A typical engine output power 101 versus engine speed 102 plot is shownin FIG. 1. Curves 103, 104, 105, 106 and 107 represent typical maximumengine power output versus engine speed for recommended uses as oftenspecified by the engine manufacturer. Examples of types of uses are:

-   -   service 103 where maximum power is required for periodic        overloads;    -   high intermittent service 104 and low intermittent service 105        where maximum power and/or speed are cyclic;    -   continuous service 106 where power and speed are cyclic;    -   continuous heavy duty service 107 where the engine is operated        at maximum power and speed without interruption or load cycling.

Locomotives typically operate in service where power and speed arecontinuous but cyclic and where the locomotive periodically requiresoperation at maximum overload power. A high speed operating point 108where the output voltage of the alternator/rectifier requires no boostis shown along with a low speed operating point 109 where the outputvoltage of the alternator/rectifier requires a boost to continue toprovide power to a DC bus.

A typical engine output torque 201 versus engine speed 202 plot is shownin FIG. 2. Curves 203, 204, 205, 206 and 207 represent the torque at thecorresponding power and speeds shown by curves 103, 104, 105, 106 and107 of FIG. 1. Torque is proportional to power divided by rotary speedand therefore decreases with increasing engine speed when output poweris approximately constant. A high speed operating point 208 is shownalong with a low speed operating point 209, corresponding to theoperating points 108 and 109 respectively of FIG. 1.

For a locomotive utilizing multiple diesel engines, the following areexamples of how diesel engines may be operated in various modes. As canbe appreciated, similar operating modes may be used for other types ofengines.

Examples of operating modes include:

-   -   maximum fuel efficiency mode    -   minimum emissions mode (whether of a substance or energy, such        as noise)    -   a combination mode of good fuel efficiency and low emissions    -   maximum power mode    -   an optimum engine lifetime mode

As can be appreciated, engines may be selected to operate in differentmodes at the same time. For example, some engines may be operated in afuel efficient mode while others are operated in a low emissions modesuch that, for example, the locomotive as a whole is operated at adesired overall fuel efficiency and emissions performance level.

These engines also have specific fuel consumption and emissions levelmaps such as shown in FIGS. 3 and 4.

A typical diesel engine fuel map is shown in FIG. 3. In this example,engine output power 301 is plotted versus engine speed 302. The power istypically in kW and the speed is typically in revolutions per minute(“rpms”). In some fuel maps, engine output torque may be plotted versusengine speed but in the present invention it is preferable to plot powerversus speed. The maximum recommended power for a specific type of use(described previously in FIG. 1) available at any engine speed is shownby the power limit curve 303. Contours 304 of constant specific fuelconsumption are also shown. The contours 304 are typically expressed asgrams of fuel consumed per kW-hr of output energy or liters of fuelconsumed per kW-hr of output energy. In the example contours shown inFIG. 3, the specific fuel consumption values of each contour are shownexpressed grams of fuel consumed per kW-hr. In FIG. 3, a nominalpredetermined operating point 305 is shown. A maximum fuel efficiencyoperating point 306 is shown where the output power and engine speed arelower than the nominal operating point. A minimum NOx emissionsoperating point 307 (described further in FIG. 4) is shown where theoutput power and engine speed are also lower than the nominal operatingpoint and at a significantly lower power than the maximum fuelefficiency operating point 306. Operating points 308 all representcombinations of both lower specific fuel consumption and NOx emissionsas compared to the nominal operating point 305. Operating point 309 isan example of increased output power at the same engine speed as thenominal operating point 305. This operating point may be selected for,for example, by the requirement for a short burst of maximum power forrapid acceleration. Typically, the control system on an engine can allowan engine to run at a higher power rating for a limited time, then willautomatically derate the engine to a lower power curve after thespecified time period has elapsed. Finally, operating point 310 is anexample of reduced output power at the same engine speed as the nominaloperating point 305 which may be selected for increasing enginelifetime. A combination of slightly increased engine speed and/orreduced operating power (as compared to the nominal operating point 305)may also be used to increase engine lifetime due to reduced internalpressures and stresses in the combustion cycle of the engine. The aboveillustrates an example of the use of a fuel map for determining aselected engine operating mode.

A typical NOx emissions map is shown in FIG. 4. In this example, whichcorresponds to the fuel map of FIG. 3, engine output power 401 isplotted versus engine speed 402. The power is typically in kW and thespeed is typically in revolutions per minute (“rpms”). In some emissionsmaps, engine output torque may be plotted versus engine speed but in thepresent invention it is preferable to plot power versus speed. Themaximum recommended power for a specific type of use (describedpreviously in FIG. 1) at any engine speed is shown by the power limitcurve 403 and corresponds to the limit curve 103 in FIG. 1. Contours 404of constant specific NOx emissions are also shown. The contours 404 aretypically expressed as grams of NOx emitted per kW-hr of output energy.In the example contours shown in FIG. 4, the specific NOx emissionvalues of each contour are shown expressed grams of NOx emitted perkW-hr. In FIG. 4, a nominal predetermined operating point 405 is shownwhich corresponds to the nominal operating point 305 of FIG. 3. Amaximum fuel efficiency operating point 406, a minimum NOx emissionsoperating point 407, a maximum power operating point 409 and a optimumengine lifetime operating point 410 are also shown and correspond to themaximum fuel efficiency, minimum NOx emissions, maximum power andoptimum engine lifetime operating points of FIG. 3. Similarly, operatingpoints 408 represent 20 combinations of both lower specific fuelconsumption and NOx emissions compared to the nominal operating point405.

As can be seen, both fuel and emissions maps are used to select adesired operating mode, since, in general, fuel consumption improveswith decreasing engine speed with little change in NOx emissions levels,while NOx emissions can be reduced with a reduction in power but at theexpense of increased fuel consumption. As can be appreciated, operatingpoints may also be selected to minimize particulate and other emissionsusing similar maps relating to these emissions.

In each of the following examples, the locomotive power settings arebased on a low idle setting; a high idle setting and power notchsettings from 1 to 8. As can be appreciated, a locomotive may only havea single idle setting. The same operating mode strategy can be appliedto a multiple engine locomotive having between two and about eightseparate engines where the engines need not have the same power ratingsince all engines are assumed to output DC electrical power to a commonDC bus (a so-called electric transmission).

Typically a diesel-electric locomotive is operated by selecting adesired power level for the locomotive. These power settings usuallycorrespond to an idle setting or settings and eight power notchsettings. Thus when an engineer selects a particular power setting, thelocomotive's controller apparatus controls the engines and tractionmotors until the desired power to the traction motors is achieved.

Table 1 illustrates the output brake horsepower (“BHP”) versus enginespeed (“rpm”) for a single industrial engine such as might be used for alarge truck. This engine is typical for an engine having an outputhorsepower in the range of 600 to 700 BHP and illustrates a possible BHPversus rpm settings for use as one of a number of engines that could beused in a multi-engine locomotive.

FIG. 5 is a plot of engine power 501 versus engine speed 502 for asingle engine at a preferred condition. The two idle settings (low idleand high idle) are represented by triangles 504. The eight notchsettings are represented by squares 503. This might represent amanufacturer's recommended settings for use on a locomotive where themanufacturer has recommended performance that optimizes for examplepower, fuel economy and engine lifetime.

Multi-Engine Operating Options

The application of various possible operating modes for a multipleengine locomotive based on six engines is illustrated in the followingdiscussion where these examples are based on the typical engine ofTable 1. As can be appreciated, the engine of Table 1 can be operatedwith different combinations of power and speed, depending, for example,on the duty cycle anticipated for the engine, peak power requirements,fuel economy and emissions levels, as was discussed previously in FIGS.1 through 4.

In a first operating mode for a multi-engine locomotive, each powersetting corresponds to a preselected locomotive power level which isobtained by a set number of engines each set at the same power level andrpm for each notch setting. This is illustrated in Table 2. Table 2shows that as notch power is increased, the number of engines requiredvaries and the speed of all the selected engines is the same. Thispreset operating mode is known and has been disclosed for example in apresentation entitled “Multi-Engine GenSet Ultra Low EmissionsRoad-Switcher Locomotive National Railway Equipment Co.”, by US EPA NewEngland, March 2006. The plot of power versus notch setting for thispreset engine schedule is shown in FIG. 6. FIG. 6 shows a plot of totallocomotive output power 601 versus the eight power notch settings 602.

When a variable number of engines are activated, the engines may beoperated at different power and speed settings to achieve differentoperating modes but the power developed at each notch setting isapproximately the same and is typically specified by the locomotiveowner and/or operator. Thus all the total locomotive power outputs 603are approximately the same for the different engine operating modes. Theexception is the operating mode whereby a fixed number of engines isspecified and in this case the total locomotive power output is lowerfor the higher notch settings 604.

This simple first operating mode can present difficulties when theengineer goes back and forth in notch settings as might be done forexample in yard switching operations. Engines and their associatedstarter motors will wear out quickly if engines are turned on and offfrequently.

A procedure that would improve the wear and tear on engines that areturned on and off frequently is to include an algorithm in thecontroller (a PLC or computer for example) that keeps an engine in lowor high idle for a selected period of time after it has been deselected(as for example when moving from notch 8 to notch 7 in the example ofTable 2). A further strategy that can retain a high degree ofresponsiveness is to always have one unused engine idling at high idleso that when additional power is requested, the engine at high idle canbe brought on-line quickly. Additionally, one of the engines at low idlecan then automatically be increased to high idle to put another unusedengine at the ready for additional power increases.

In a second operating mode, each power setting approximately correspondsto the preselected locomotive power level which is obtained by a setnumber of engines as in the first operating mode. However, in the secondoperating mode, the last engine selected is operated at a differentpower level and speed than the previously engaged engines. This isillustrated in Table 3. The plot of power versus notch setting for thispreset engine schedule is approximately the same as that shown in FIG.6. The advantage of this mode is that all but one of the engaged enginescan be operated at a speed (rpm) such as for example at an optimumdesired rpm as shown in Table 3.

In a third operating mode, each power setting can correspond to apreselected locomotive power level which is obtained by bringing anotherengine on-line as soon as the currently operating engines reach acertain percentage of their rated power. This is illustrated in Table 4.In this example, when the engines that are providing power to the DC busexceed a certain percentage of their power rating (say about 60% toabout 85%), then an additional engine is brought on line. As can be seenby comparing Table 2 and Table 4, the number of engines selected foreach notch setting is different for the intermediate notch settings eventhough the locomotive power versus notch setting is approximately thesame for both examples as shown in FIG. 6. This third operating mode isalso known and has been disclosed for example in a press releaseentitled “French Railway Company Voies Férées Légères et Industrielles(VFLI) Puts Its Trust in Deutz Engines”.

This simple third operating mode can also present difficulties when theengineer goes back and forth in notch settings as might be done forexample in yard switching operations. Engines and their associatedstarter motors will wear out quickly if engines are turned on and offfrequently. As discussed in relation to the first operating mode, aprocedure that would improve the wear and tear on engines that areturned on and off frequently is to include an algorithm in thecontroller that keeps an engine in low or high idle for a selectedperiod of time after it has been deselected. A further strategy that canretain a high degree of responsiveness is to always have one unusedengine idling at high idle so that when additional power is requested,the engine at high idle can be brought online quickly. Additionally, oneof the engines at low idle can automatically be increased to high idleto put another unused engine at the ready for additional powerincreases.

In a fourth operating mode, the engineer selects the number of enginesto be used and that number remains unchanged until the engineer changesit. An example of this mode is illustrated in Table 5. This is aparticularly practical option for moving the locomotive around aswitching yard; moving the locomotive to a new location; or doing lowspeed switching operations (from about 0 to about 5 mph for example)where, for example, two engines can provide the required tractiveeffort. FIG. 6 shows a plot of total locomotive output power 601 versusthe eight power notch settings 602 and illustrates this operating mode(a fixed number of engines specified) with the notch power settings 604.

In a fifth operating mode, each power setting is met by operating aselected number of engines in their most fuel efficient mode. This wouldbe done automatically by a controller programmed to use specific fuelconsumption maps such as shown in FIG. 3 for each engine and to optimizethe engine's power and rpm settings to obtain the lowest fuelconsumption at each power setting. An example of this is shown in Table6.

In a sixth operating mode, each power setting is met by operating aselected number of engines in their lowest emissions mode. This would bedone automatically by a controller programmed to use specific emissionsoutput maps such as shown in FIG. 4 for each engine and to optimize theengine's power and rpm settings to obtain the minimum emissions outputat each power setting. An example of this is shown in Table 7. Thiscould be done for any number of emissions categories such ashydrocarbons (HC), carbon monoxide (CO), nitrous oxides (NOxs) andparticulate material (PM) or a combination of these emissions variables.

In the present invention, the locomotive would include a control panelor computer screen that would allow the locomotive engineer to selectfrom a number of available engine operating modes such as for examplethe six operating modes described above. The present invention wouldhave available for engineer selection at least 2 operating modes andpreferably 3 or more operating modes.

As can be appreciated, the engines can be operated at the same powerlevels and speeds (rpm)s or they can each be operated at different powerlevels and rpms to achieve a desired operating mode. It is noted thatmost of the above operating modes can be achieved for a singlepreselected locomotive power versus notch setting schedule.

Multi-Engine with Energy Storage Configuration

The same operating strategies can be applied to a hybrid locomotivewhich is comprised of several engines and an energy storage system. Thefollowing examples of control modes are based on a hypotheticallocomotive having four identical engines (for example each engine mayhave a rated power of 600 HP), each engine having a power versus rpm anda torque versus rpm curves such as a shown in FIGS. 1 and 2 and anenergy storage unit comprised of a battery pack with a rating of, forexample, 1,800 amps maximum at a peak power of 450 kW (600 HP). In thisexample, the energy storage unit has a maximum power rating of roughlythe same as the engines.

The battery pack is an instantaneous source of power and therefore canbe used to provide power when the notch setting is advanced but before anew engine can be started, or an engine brought up to speed from lowidle. The locomotive can be provided with a control panel that allowsthe engineer to use only the battery pack if for example, a momentarypower surge is required and it would be inefficient to start anotherengine or bring another engine on-line from idle.

A possible mode of hybrid operation is shown in Table 8 which isobtained by a prescribed number of engines augmented by an energystorage battery pack for each notch setting. In the top portion of Table8, the battery is used to power the locomotive when idling and travelingin notch 1. Engines are brought on line for higher notch settings butwhen the battery can supplement the power required, the battery is usedin place of an additional engine. This scenario is an example of a 2,500HP hybrid locomotive. In the event of sustained operation at any of thehigher notches where the energy storage capacity of the battery packdrops below a desired state-of-charge, the locomotive may be operated aton engine power only. In this example, there is some reduction in powerdeveloped at the maximum power setting of notch 8. The power versusnotch setting for this hybrid locomotive configuration would beapproximately is shown in FIG. 7.

FIG. 7 shows a plot of total locomotive output power 701 versus theeight power notch settings 702. For either full hybrid operating mode orthe low power hybrid operating mode, the total locomotive power outputs603 703 are the same except for notch 8. In this example, the power forthe full hybrid mode in notch 8 704 is slightly higher than the powerdeveloped for low power hybrid mode in notch 8 705.

Another operational strategy is to use the battery pack in a powercompression role. For example, the 4 engine locomotive can be operatedwith 3 engines and a battery pack where the battery pack is continuallycharged by the remaining engine set on high idle. This mode would beeffective if the locomotive were standing by for long periods of timebut be required to provide a substantial power surge at low to moderatespeeds.

Multi-Engine Configurations

The present inventions include multi-engine locomotive configurationswhere the engine systems are connected (1) in parallel to a common DCbus; (2) in series with a common DC bus; or in combinations of paralleland series. The first two configurations require different strategies tomeasure individual engine system output power and to ensure that eachengine system is contributing the desired amount of power to the DC bus.

Parallel Configuration

In parallel configuration, the output voltage of an engine systemproviding power to the DC bus is very close to the voltage measured onthe DC bus, If, for example, the output voltage of an engine system isjust below bus voltage then that engine system will not provide anypower to the DC bus. However, a measurement of the output current of anengine system is a sensitive and direct measurement of the enginesystem's power output and is the preferred method of determining enginesystem output power. An engine system's output power is its outputcurrent times the DC bus voltage. In parallel configurations, thegeneral method of ensuring the desired engine system output power isthen:

-   -   set the desired DC bus voltage or bus voltage range and measure        the DC bus voltage    -   for each engine system, measure its output current and use this        to determine its output power (engine system current times DC        bus voltage)    -   if the engine system is not outputting the desired power, adjust        an engine system electrical or mechanical parameter to produce        desired engine system output current and hence power

FIG. 8 is a schematic of the principal propulsion components of alocomotive showing an example of five engine systems 803 connected inparallel to a DC bus represented by bus bars 801 and 802 to providepower to four traction motors 807 each individually controlled throughits own power control device 808. If the traction motors are AC motors,the power control devices are inverters. If the traction motors are DCmotors, the power control devices are choppers. The same principles canbe applied to any number of engines in the range of two engines to abouteight engines. Eight engines could in principle correspond to the eightnotches of power control typically used in many locomotives. Thisexample illustrates how a number of smaller engines which may havehighly developed efficiency and emission controls can be used in placeof a single large 20 engine. In this example, four traction motors areused but, as can be appreciated, the number and type of drive motors isindependent of the number and type of power supplies. The DC bus alsoprovides power to an auxiliary power system 810 through a buck or boostcircuit 811. Also shown is an optional dynamic braking system comprisedof a power dissipating resistor grid 812 controlled by a switch 813.Each engine 804 is shown has its mechanical shaft power converted to DCelectrical output by an alternator 805 whose AC output is converted toDC output by a rectifier 806 which, in turn, is connected to the DC bus.An engine system 803 is comprised of an engine 804 its mechanical outputshaft 814 which drives its corresponding alternator 805 and rectifier806. The voltage levels and power outputs of the engine systems arecontrolled independently by their individual electrical (alternatorexcitation for example) or mechanical (fuel supply control for example)means incorporated in their engine systems.

The rectifiers are commonly comprised of blocking diodes to preventreverse power flow from the DC bus when the DC output voltage of aparticular engine system is less than the voltage across the DC bus. Ascan be seen, the voltage across the DC bus is established by the enginesystem or systems with the highest DC output voltage to the bus. Enginesystems with lower output DC voltages than the voltage across the buswill not provide power to the bus and will not receive power from thebus because of the blocking diodes contained in their rectifiers. Thus,by controlling the output voltage of any engine system by its particularelectrical or mechanical control means, that engine system can bebrought on-line to supply power to the DC bus. In this example, the DCbus supplies power to a load control apparatuses 808 which control thelevel of power to each of the four traction motors 807. The bus providesa power capacity at in a predetermined voltage range and the loadcontrol apparatuses 808 control the current flows in each traction motor807, and hence the power level, to the motors 807. The traction motors807 may be, for example, AC induction motors, DC motors, permanentmagnet motors or switched reluctance motors. If the traction motors areAC motors, power is controlled by means of one or more invertersconnected to the DC bus.

Alternately, if the traction motors are a DC motors, power is controlledby means of one or more chopper circuits connected to the DC bus. In theexample shown in FIG. 8, each traction motor has its own load controlapparatus Although not shown here, locomotives may be configured with asingle load control apparatus to control all of the traction motors.

FIG. 9 is an example of the overall electrical schematic of amulti-engine locomotive with five engine systems 901 connected inparallel to a DC bus. The engines are all shown with wound rotoralternators 902 and rectifiers 903 although the engine systems may be ofdifferent sizes and types and the alternators may be permanent magnetmachines, asynchronous alternators such as induction alternators, DCgenerators, or switched reluctance generators. The output DC currentfrom each prime power system is measured by its own individual currentsensor 904. These five prime power systems are the principal powersources providing power to a DC bus shown by conductors 905 and 906.

The circuit of FIG. 9 also includes a propulsion system 907 shown herewith four traction motors, an auxiliary power system 908 with itsvoltage control circuit 909. The circuit also includes a resistive grid910 and switch 911 that provides a dynamic braking capability. Thislocomotive power circuit is an example of a multi-prime power sourcelocomotive with regenerative braking capability that could be used, forexample, as a road switcher. A similar electrical architecture for amulti-engine locomotive was disclosed previously in U.S. patentapplication Ser. No. 11/200,881 filed Aug. 9, 2005 entitled “LocomotivePower Train Architecture”.

Control and Balancing of Multi-Engine in Parallel

FIG. 10 is an overview flowchart showing the primary steps in amulti-engine control loop with multiple engines in parallel. In FIG. 10,step 1001 determines all the inputs required to set locomotive powerrequirements, select engines, set the DC bus voltage, sets the power andspeed of the engines, balance the flow of power from the engines andadjust the load if load control is available. Step 1002 is where thepower requirements for the locomotive are established depending on anumber of variables determined in step 1001. In step 1003, engines areselected. This includes the number of engines, the specific engines,which engines need to be activated for future use and which engines canbe deactivated. In step 1004, the DC bus voltage is selected. A specificoperating voltage is selected for the load control embodiment. The DCbus voltage is not determined in the embodiment which has no loadcontrol. In step 1005, the power and speed (rpms) of each engine is setbased on the power requirements and engine operating mode determined instep 1002. In step 1006, the power outputs of all engines are measuredby measuring current output from each alternator/rectifier systems. Inthis step, the power outputs are balanced so that each engine iscontributing its pro rata share of the output power. This step is morepreferably accomplished by adjusting excitation current to achieve therequired alternator/rectifier output current. This step may also beaccomplished by adjusting engine speed (rpms) to achieve the requiredalternator/rectifier output current. This step is may alternately beaccomplished by adjusting engine fuel rate control. Finally, in step1007, the load is adjusted if load control is used. In this step thepower to the load is adjusted to equal the power available from the DCbus. This is accomplished for example by choppers which regulate DCtraction motors or inverters which regulate AC motors.

FIG. 11 is an example of a main flow chart of automated decision makingfor controlling the overall multi-engine selection operating andbalancing process with multiple engines in parallel. This cycle ofdecisions can be executed continuously (for example every millisecond)or intermittently (for example every 1 second) or at intervals inbetween by a predetermined computer program or by a computer programthat adapts, such as for example, a program based on neural networkprinciples. As can be appreciated, many of the steps can be carried outin different sequences and some of the steps may be optional.

As is common practice, the choices of applying traction power, applyingdynamic braking or operating the locomotive at idle to supply auxiliarypower are made by the locomotive engineer or operator utilizing controlsin the cab, or via a remote-control or equivalent system when, forexample, in a switch yard.

As shown in the example of FIG. 11, an automated cycle begins 1101. Thefirst step 1102 is to estimate the power requirements and operating modeof the locomotive. In step 1103, the requirement for additional enginescurrently deactivated is established from step 1102. If additionalengines are required, then the number of currently deactivated enginesthat must be activated is determined in step 1104. This engineactivation step is described more fully in FIG. 17. The engineactivation procedure is implemented in step 1105 and the cycle thencontinues 1106. As noted above, the locomotive operating mode iscommonly set by the locomotive's engineer. These are (1) a notch 1 to 8power setting 1107, (2) an idle setting 1108, or (3) a dynamic brakingsetting 1109. For each of three power modes, it is possible that one ormore engines may be deactivated. Deactivation means idling an engine sothat it does not provide power to the DC bus, or shutting off theengine. The deactivation of engines is controlled in step 1110. Step1111 returns to the beginning of the main control cycle.

FIG. 12 is an example of a flow chart for selecting and configuringengines for any of the notch 1 to 8 power settings 1200 with no loadcontrol with multiple engines in parallel, FIG. 12 shows an example of aflow chart for automated selection and configuration of engines for anyof the notch 1 to 8 power settings 1200. This figure illustrates theprocess for a locomotive that does not have an independent means of loadcontrol. That is, the traction motors may be able to consume more powerthan the engines can provide, depending on engine alternator excitationsettings and traction motor volts which are a function of locomotivespeed. The first step 1201 is to determine the power associated with thenotch number selected by the engineer and to determine the locomotivespeed. The latter can be determined from a number of well-known meanssuch as for example by a speedometer, by measuring axle rpms, by using aradar system and the like. Each notch number is typically associatedwith a predetermined power level at each locomotive speed, notch 1 beingthe lowest power setting and notch 8 being the highest power setting. Ascan be appreciated, the power level associated with each notch settingcan be varied from time to time by reprogramming an on-board computer.

The next step 1202 is to determine the desired engine operating mode.Examples of operating modes, which were previously illustrated in FIGS.3 and 4, include a maximum fuel efficiency mode, a minimum emissionsmode, a combination mode of good fuel efficiency and low emissions, anoptimum engine lifetime mode, and a maximum power mode. The choice maybe determined by the engineer or by a predetermined algorithm based ondata from the locomotive's route location and requirements for the zonein which the locomotive or consist member is operating.

The next step 1203 is to determine the number of engines operative toprovide power to the DC bus. Step 1203 may be carried out by analgorithm controlled by an onboard computer. It may also be based on apredetermined lookup table which associates each notch, each appropriatelocomotive speed range and its various operating modes with an operatingpoint such as described in FIGS. 3 and 4. It is also possible that, atsome notch settings, all but one of the engines can be set at or nearthe selected operating points and the all but one engine can be used tobalance out the total selected notch power by being set at a non-optimumoperating point. Alternately, the all but one engine can be used tobalance out the total selected notch power by using its alternatorvoltage boost to independently control its output voltage and thus canalso be set at a its optimum operating point. This provides a degree ofcontrol over power output and operating points that is not availablewith a single large engine. A single large engine can be set at only onepower and speed setting and often has to trade off better fuel economyfor low emissions. In a multiple engine locomotive, all but one of thepower-producing engines (or all when alternator boost is available) canbe tuned to optimize power, fuel consumption and emissions and often theone engine can be operated near its optimum operating point. In the step1203 where all the engines are the same, selection of the number ofengines operative to provide power to the DC bus is typically done bydividing the power requirement determined in step 1201 by the powerrating of the engines and rounding the resulting number upwards. In thecase where there are engines of differing power ratings, the selectionalgorithm may be more involved so as to balance the power contributionfrom each engine. In either case, the algorithm that selects the numberof engines may consider the operating history of the engines, asindicated by step 1204, so as to avoid using some engines more thanothers and thereby approximately balancing the usage and maintenanceperiod of the engines. An engine log typically contains information onengine usage (hours, fuel consumption, lubricant consumption, totalrpms, megawatt-hours, hours in idle modes, hours in the various notchsettings and hours in dynamic braking and the like) and maintenancehistory. Although less preferable than consulting an engine log, theselection algorithm may be engine selection by a random number betweenone and the number of available engines, which, over time, should tendto even out engine usage. The selection algorithm may be engineselection by rotation to the next engine in an engine sequence which,over time, should also tend to even out engine usage. In the next step1205, a selected engine may need to be derated. For example, theselected engine may have one or more cylinders operating at less thanoptimum rating, the engine's control system may automatically derate theengine to a lower power after a specified time period of operating at ahigher-than-normal power rating or any number of other well-knownreasons for derating engine performance. If an engine is required to bederated 1206, then the procedure returns to step 1203 to re-select thenumber of engines since the derated engine may require an additionalengine to provide the requested power. In the next step 1207, theengines not selected for providing power to the DC bus are identifiedfor deactivation and may be selected to be idled or shut down to bedeactivated. This deactivation procedure is controlled in step 1113 ofthe main flow chart (FIG. 11) and fully described in FIG. 16.

In the next step 1208, the DC bus voltage is measured and compared withthe selected range for the DC bus voltage for that notch setting. As thepower consumed by the load (traction motors) increases beyond theoptimum engine power capacity, the engine speeds will begin to decrease.In step 1209, typically a load variable such as total load current ortorque is measured and used in a first control feedback loop to increaseengine speeds by decreasing their alternator excitation currents whichtends to decrease alternator output voltages. As this occurs for all theengines, the DC bus voltage drops, reducing the power to the load byreducing motor voltage until the total engine power output matches thepower required by the load. This is a stable feedback process commonlycarried out automatically for each engine by one of a number ofwell-known proportional integral differential (“PID”) controlalgorithms. Thus, the DC bus voltage may be highly variable, typicallyranging from near zero volts to well over 1,000 volts. The next step1210 begins an internal control loop 1250 for each engine to obtain abalanced power flow from each engine. Each engine has a fuel map whichis typically a plot of engine power or torque versus engine rpms forvarious contours of constant specific fuel consumption, and an emissionsmap which is typically a plot of engine power or torque versus enginerpms for various contours of constant specific NOx emissions. As can beappreciated, there may be additional emissions maps for hydrocarbons andparticulate matter and the like. In step 1211, the rpms of the selectedengine is determined so as to produce the required power at the specificfuel consumption and emissions rate corresponding to the operating modeselected in step 1202. In step 1212, the excitation current for thealternator of each engine is selected to provide an alternator outputvoltage to fall within the range of the DC bus voltage measured in step1208. When available, the amount of alternator boost may also be used togenerate output voltage to fall within the range of the DC bus voltagemeasured in step 1208. This latter capability may be useful for examplewhen an engine is derated or when an engine is operated at a lower powerand rpm so that the engine may continue to supply power to the DC bus byhaving independent control over its alternator output voltage.

Step 1213 is a step where the current is measured at the output of eachalternator's rectifier. This current, which is at the DC bus voltage, isa direct measure of the power flowing from the selected engine. Anoutput current measurement is a sensitive and direct measure of poweroutput of the alternator/rectifier apparatus to the DC bus. The measuredcurrent is used in a second control feedback loop to modify the engine'salternator excitation current to bring the engine's power contributioninto balance with its pro rata portion of the total power to the DC bus.In the case where all engines are set to the same output power, eachengine is balanced to deliver the same amount of power as the otherengines to within a predetermined tolerance, preferably in the range ofabout ±5%. This second control feedback loop is designed to be a stablefeedback process commonly carried out automatically for each engine byone of a number of well-known proportional integral differential (“PID”)control algorithms.

The next step 1214 is executed for all engines after all engines havebeen balanced via internal control loop 1250. In step 1215, the totalpower from all engines to the DC bus is determined, preferably bymeasuring the currents at the output of each alternator's rectifier andmultiplying the sum by the measured DC bus voltage. Once the allocationof power to the traction motors is determined 1215, the algorithmproceeds to the engine deactivation control loop 1216.

FIG. 13 is an example of a flow chart for selecting and configuringengines for any of the notch 1 to 8 power settings 1300 with loadcontrol with multiple engines in parallel. This figure illustrates theprocess for a locomotive that has an independent means of load controlwhich is a preferred embodiment. That is, the power distributed to thetraction motors is controlled independently such that the total powerdistributed to the load is controlled independently to match the poweravailable from the engines. This may be done for example by using one ormore choppers at the output of the DC bus to DC traction motors, or byusing one or more inverters at the output of the DC bus to AC tractionmotors. The first step 1301 is to determine the power associated withthe notch number selected by the engineer and to determine thelocomotive speed. As can be appreciated, the power level associated witheach notch setting can be varied from time to time by reprogramming anon-board computer. The next step 1302 is to determine the desired engineoperating mode. Examples of operating modes are described in thediscussion of FIG. 12. The choice may be determined by the engineer orby a predetermined algorithm based on data from the locomotive's routelocation and requirements for the zone in which the locomotive orconsist member is operating.

The next step 1303 is to determine the number of engines operative toprovide power to the DC bus. Step 1303 may be carried out by analgorithm controlled by an onboard computer. It may also be based on apredetermined lookup table which associates each notch, each appropriatelocomotive speed range and its various operating modes with an operatingpoint such as described in FIGS. 3 and 4. It is also possible asdescribed previously that, at some notch settings, all but one of theengines can be set at or near the selected operating points and oneengine can be used to balance out the total selected notch power bybeing set at a non-optimum operating point. In the step 1303 where allthe engines are the same, selection of the number of engines operativeto provide power to the DC bus is typically done by dividing the powerrequirement determined in step 1301 by the power rating of the enginesand rounding the resulting number upwards, In the case where there areengines of differing power ratings, the selection algorithm may be moreinvolved so as to balance the power contribution from each engine. Ineither case, the algorithm that selects the number of engines mayconsider the operating history of the engines, as indicated by step1304, so as to avoid using some engines more than others and therebyapproximately balancing the usage and maintenance period of the engines.Although less preferable than consulting an engine log, the selectionalgorithm may be engine selection by random number between one and thenumber of available engines, which, over time, should tend to even outengine usage.

The selection algorithm may be engine selection by rotation to the nextengine in an engine sequence which, over time, should also tend to evenout engine usage. In the next step 1305, a selected engine may need tobe derated. If an engine is required to be derated 1306, then theprocedure returns to step 1303 to re-select the number of engines sincethe derated engine may require an additional engine to provide therequired notch power. In the next step 1307, the engines not selectedfor providing power to the DC bus are identified for deactivation andmay be selected to be idled or shut down to be deactivated.

This deactivation procedure is controlled in step 1113 of the main flowchart (FIG. 11) and fully described in FIG. 16.

In the preferred load control embodiment, the next step 1308 is tomeasure the DC bus voltage and set the desired nominal value and rangefor the DC bus voltage. The range is preferably ±75 volts from thenominal DC bus voltage, more preferably ±50 volts from the nominal DCbus voltage, and most preferably ±25 volts from the nominal DC busvoltage. This voltage may be set at a different predetermined nominalvalue for each notch setting, or at a predetermined nominal value for arange of notch settings, or at the same predetermined nominal value forall notch settings.

The next step 1309 begins an internal control loop 1350 for each engineto obtain a balanced power flow from each engine. Each engine has a fuelmap and an emissions map or maps. In step 1310, the rpms of the selectedengine is determined so as to produce the required power at the specificfuel consumption and emissions rate corresponding to the operating modeselected in step 1302. In step 1311, the excitation current for thealternator of each engine is selected to provide an alternator outputvoltage to match the selected DC bus voltage. Step 1312 is a step wherethe current is measured at the output of each alternator's rectifier.This current which is at the DC bus voltage is a direct measure of thepower flowing from the selected engine. An output current measurement isa sensitive and direct measure of power output of thealternator/rectifier apparatus to the DC bus. The measured current isused in a control feedback loop to modify the engine's alternatorexcitation current to bring the engine's power contribution into balancewith its pro rata portion of the total power to the DC bus. In the casewhere all engines are set to the same output power, each engine isbalanced to deliver the same amount of power as the other engines withina predetermined tolerance, preferably about ±5%. This control feedbackloop is designed to be a stable feedback process commonly carried outautomatically for each engine by one of a number of well-knownproportional integral differential (“PID”) control algorithms.

The next step 1313 is executed for all engines after all engines havebeen set via internal control loop 1350. In step 1314, the total powerfrom all engines to the DC bus is determined, preferably by measuringthe currents at the output of each alternator's rectifier andmultiplying the sum by the measured DC bus voltage. If the total poweris too low 1315 to provide the required power to the traction motors,then the power to selected traction motors is reduced 1316 to the amountof power available from the DC bus. This power reduction can be madeequal to all traction motors or can be allocated based on an algorithmthat considers each powered wheel-set separately. The latter is anavailable strategy if each traction motor has its own power controlapparatus (such as a chopper circuit for each DC traction motor or aninverter for each AC traction motor).

Power may be selectively reduced for example on the leading wheel set inwet conditions. Once the allocation of power to the traction motors isdetermined 1314, the algorithm proceeds to the engine deactivationcontrol loop 1317.

In a locomotive without an independent means of load control, if theengine power is too low to provide the required power to the tractionmotors, then (1) the engine power may be adjusted upwards or (2) thepower to traction motors may be reduced by lowering the alternatorexcitation current until the alternator output voltage matches thetraction motor voltage. In the preferred multi-engine locomotive controlmeans of the present invention, if the total power from the engines istoo low to provide the required power to the traction motors, thenpreferably the power to traction motors is reduced by a small amount toequal the power available. Alternately, another engine may be added toprovide the necessary power in all but the highest notch setting. At thehighest notch setting, it is still possible to increase the power outputof one or more engines for periodic overloads. Thus, the control andbalancing of output power from the engines can always be separatelyadjusted from the load power requirements of the traction motors bycontrolling a predetermined maximum load on the engines.

FIG. 14 shows an example of a flow chart for automated selection andconfiguration of multiple engines in parallel for any of number of idlesettings 1400.

Typically, a locomotive has a high idle and a low idle setting. Thelatter may be used, for example, to minimize fuel consumption for longperiods of idle. This figure illustrates the process for a locomotivethat has an independent means of load control similar to that describedin FIG. 13, which is a preferred embodiment. As can be appreciated, theprocess can be modified for a locomotive that does not have anindependent means of load control such as described in FIG. 12. The nextstep 1402 is to determine the desired engine operating mode. Examples ofoperating modes are described in the discussion of FIG. 12. The choicemay be determined by the engineer or by a predetermined algorithm basedon data from the locomotive's route location and requirements for thezone in which the locomotive or consist member is operating. The nextstep 1403 is to determine the number of engines operative to idle andprovide power to the DC bus. Step 1403 may be carried out by analgorithm controlled by an on-board computer. It may also be based on apredetermined lookup table which associates each idle setting and itsvarious operating modes with an operating point such as described inFIGS. 3 and 4. It is also possible that, at some idle settings, all butone of the engines can be set at or near the selected operating pointsand the all but one engine can be used to balance out the total selectedidle power by being set at a non-optimum operating point. Alternately,the all but one engine can be used to balance out the total selectednotch power by using its alternator voltage boost, if available, toindependently control its output voltage and thus can also be set at aits optimum operating point. This provides a degree of control overpower output and operating points that is not available with a singlelarge engine. In the step 1403 where all the engines are the same,selection of the number of engines operative to provide power to the DCbus is typically done by dividing the power requirement determined instep 1401 by the power rating of the engines and rounding the resultingnumber upwards. In the case where there are engines of differing powerratings, the selection algorithm may be more involved so as to balancethe power contribution from each engine. In either case, the algorithmthat selects the number of engines may consider the operating history ofthe engines, as indicated by step 1404, so as to avoid using someengines more than others and thereby approximately balancing the usageand maintenance period of the engines. Although less preferable thanconsulting an engine log, the selection algorithm may be engineselection by random number between one and the number of availableengines, which, over time, should tend to even out engine usage. Theselection algorithm may be engine selection by rotation to the nextengine in an engine sequence which, over time, should also tend to evenout engine usage. In the next step 1405, a selected engine may need tobe derated. If an engine is required to be derated 1406, then theprocedure returns to step 1403 to re-select the number of engines sincethe derated engine may require an additional engine to provide therequired idle power. In the next step 1407, the engines not selected forproviding power to the DC bus are identified for deactivation and may beselected to be idled but not providing power to the DC bus, or shut downto be deactivated. This deactivation procedure is controlled in step1113 of the main flow chart (FIG. 11) and fully described in FIG. 16.

In the preferred load control embodiment, the next step 1408 is tomeasure the DC bus voltage and set the desired nominal value and rangefor the DC bus voltage. The range is preferably ±75 volts from thenominal DC bus voltage, more preferably ±50 volts from the nominal DCbus voltage, and most preferably ±25 volts from the nominal DC busvoltage. This voltage may be set at a different predetermined value foreach idle setting but most preferably at the same predetermined valuefor all idle settings.

The next step 1409 begins an internal control loop 1450 for each engineto obtain a balanced power flow from each engine. Each engine has a fuelmap and an emissions map or maps. In step 1410, the rpms of the selectedengine is determined so as to produce the required power at the specificfuel consumption and emissions rate corresponding to the operating modeselected in step 1402. In step 1411, the excitation current for thealternator of each engine is selected to provide an alternator outputvoltage to match the selected DC bus voltage. When available, the amountof alternator boost may also be used to generate output voltage to fallwithin the range of the DC bus voltage measured in step 1408. Step 1412is a step where the current is measured at the output of eachalternator's rectifier. This current which is at the DC bus voltage is adirect measure of the power flowing from the selected engine. An outputcurrent measurement is a sensitive and direct measure of power output ofthe alternator/rectifier apparatus to the DC bus. The measured currentis used in a control feedback loop to modify the engine's alternatorexcitation current to bring the engine's power contribution into balancewith its pro rata portion of the total power to the DC bus. In the casewhere all engines are set to the same output power, each engine isbalanced to deliver the same amount of power as the other engines withina predetermined tolerance, preferably about ±5%. This control feedbackloop is designed to be a stable feedback process commonly carried outautomatically for each engine by one of a number of well-knownproportional integral differential (“PID”) control algorithms.

The next step 1413 is executed for all engines after all engines havebeen set via internal control loop 1450. In step 1414, the total powerfrom all engines to the DC bus is determined, preferably by measuringthe currents at the output of each alternator's rectifier andmultiplying the sum by the measured DC bus voltage. If the total poweris too low 1415 to provide the required power to provide for the idlinglocomotive, then the idle setting may be changed 1416 to a highersetting, the power provided at the selected idle setting may beincreased or the power required by the locomotive may be reduced. Areduction in the hotel power required for a passenger train idling in astation is an example of the latter. Once the allocation of power to theauxiliary power needs is set to match the available power from all theidled but power-contributing engines, the algorithm proceeds to theengine deactivation control loop 1417.

FIG. 15 shows an example of a flow chart for automated selection andconfiguration of multiple engines in parallel for dynamic braking 1500.This figure illustrates the process for a locomotive that has anindependent means of load control similar to that described in FIG. 13,which is a preferred embodiment. It is understood that the tractionmotors act as generators during dynamic braking and can provide powerback to flow to the DC bus. As can be appreciated, the power levelprovided by dynamic braking can be controlled by power control circuitsassociated with the traction motors.

The first step 1501 is to estimate the power required by the locomotiveduring the projected period that the locomotive is expected to be indynamic braking mode. This can be accomplished using the informationavailable on the locomotive's location along its route and its projectedroute. The next step 1502 is to determine whether the projected powerrequirements can be met by dynamic braking or whether some engine powerwill also be required. If all the required power can be supplied bydynamic braking 1503, then no engines need be engaged to provide powerto the DC bus. This situation can arise, for example, if the train istraveling down a lengthy grade. In this case, the power from dynamicbraking may exceed the auxiliary requirements of the locomotive and someof the dynamic braking energy may be switched to a resistive grid fordissipation. As can be appreciated, substantial auxiliary power may berequired to operate the traction motor blowers that provide coolingduring high current operation typical of dynamic braking and this mayrequire some engine power to the DC bus. In the case where dynamicbraking is intermittent or only operative for a short period, enginesmay be required to provide additional power to the DC bus. If enginesare required, they may be operated in an idle setting or a notch powersetting, depending on the locomotive's requirements. For example, a roadswitcher may not require substantial auxiliary power during braking buta commuter train with a large hotel load, may require more power than isavailable through dynamic braking alone. If engines are required, thenext step 1504 is to set the output power required by the engines.

The next step 1505 is to determine the desired operating mode of theengines. Examples of operating modes include a maximum fuel efficiencymode, a minimum emissions mode, a combination mode of good fuelefficiency and low emissions and an optimum engine lifetime mode. Thechoice may be determined by the engineer or by a predetermined algorithmbased on data from the locomotive's route location and requirements forthe zone in which the locomotive or consist member is operating.Comparable algorithms have been disclosed in US 2005/0251299 entitledEmission Management for a Hybrid Locomotive and U.S. Pat. No. 7,131,614entitled Locomotive Control System and Method, which describe systemsand methods for managing an operation of a locomotive as a function of alocation of the locomotive. However, such algorithms have never beenapplied to multiple generator set locomotives. The next step 1506 is todetermine the number of engines operative to provide power to the DCbus. This step, which is essentially the same as that described in step1204 of FIGS. 12 and 1304 in FIG. 13 is typically done by dividing thepower requirement determined in step 1504 by the power rating of theengines and rounding the resulting number upwards in the case where allthe engines are the same. In the case where there are engines ofdiffering power ratings, the selection algorithm may be more involved soas to balance the power contribution from each engine. In either case,the algorithm that selects the number of engines may consider theoperating history of the engines, as indicated by step 1507, so as toavoid using some engines more than others and thereby approximatelybalancing the usage and maintenance period of the engines. Although lesspreferable than consulting an engine log, the selection algorithm may beengine selection by random number between one and the number ofavailable engines, which, over time, should tend to even out engineusage. The selection algorithm may be engine selection by rotation tothe next engine in an engine sequence which, over time, should also tendto even out engine usage. In the next step 1508, a selected engine mayneed to be derated. If an engine is required to be derated 1509, thenthe procedure returns to step 1506 to reselect the number of enginessince the derated engine may require an additional engine to provide therequired idle power. In the next step 1510, the engines not selected forproviding power to the DC bus are identified for deactivation and may beselected to be idled but not providing power to the DC bus, or shut downto be deactivated. This deactivation procedure is controlled in step1113 of the main flow chart (FIG. 11) and fully described in FIG. 16.

In the preferred load control embodiment, the next step 1511 is tomeasure the DC bus voltage and set the desired nominal value and rangefor the DC bus voltage. The range is preferably ±75 volts from thenominal DC bus voltage, more preferably ±50 volts from the nominal DCbus voltage, and most preferably ±25 volts from the nominal DC busvoltage. This voltage may be set at a different predetermined valuedepending on the amount of power estimated from dynamic braking and fromthe power that can be supplied by the engines. It also depends whetherthe engines will provide power from an idle setting (such as for examplehigh idle) or from a notch power setting.

The next step 1512 begins an internal control loop 1550 for each engineto obtain a balanced power flow from each engine. Each engine has a fuelmap and an emissions map or maps. In step 1513, the rpms of the selectedengine is determined so as to produce the required power at the specificfuel consumption and emissions rate corresponding to the operating modeselected in step 1505. In step 1514, the excitation current far thealternator of each engine is selected to provide an alternator outputvoltage to match the selected DC bus voltage. Step 1515 is a step wherethe current is measured at the output of each alternator's rectifier.This current which is at the DC bus voltage is a direct measure of thepower flowing from the selected engine. An output current measurement isa sensitive and direct measure of power output of thealternator/rectifier apparatus to the DC bus. The measured current isused in a control feedback loop to modify the engine's alternatorexcitation current to bring the engine's power contribution into balancewith its pro rata portion of the total power to the DC bus. In the casewhere all engines are set to the same output power, each engine isbalanced to deliver the same amount of power as the other engines withina predetermined tolerance, preferably about ±5%. This control feedbackloop is designed to be a stable feedback process commonly carried outautomatically for each engine by one of a number of well-knownproportional integral differential (“PID”) control algorithms.

The next step 1516 is executed for all engines after all engines havebeen set via internal control loop 1550. In step 1517, the total powerfrom all selected engines is determined, preferably by measuring thecurrents at the output of each alternator's rectifier and multiplyingthe sum by the measured DC bus voltage. The power available from dynamicbraking is determined in step 1518. The total power available to thelocomotive or consist member is determined in step 1519 which is the sumof the power to the DC bus from the engines and dynamic braking. If thetotal power is too low 1520 to provide the required power for thebraking locomotive, then the power provided by the selected engines maybe increased 1521 or the power required by the locomotive may be reduced1521. Once the allocation of power to the auxiliary power needs is setto match the available power from the selected engines and dynamicbraking, the algorithm proceeds to the engine deactivation control loop1522.

FIG. 16 is an example of a flow chart for controlling enginedeactivation 1600 for a locomotive with multiple engines in parallel.Deactivation means idling an engine so that it does not provide power tothe DC bus; or shutting off the engine. In step 1601, 10 an engine isselected to be idled or shut down for deactivation. If shut down isselected 1602, then the look-ahead route information is queried 1603 todetermine if the engine may be needed within a first predetermined time1604 in which case the shut down selection would not be efficient. Ifthere is too little time before the engine is required again, then theidle mode for deactivation is automatically selected 1612. If there issufficient time to shut down the engine, then the engine is selected tobe turned off 1605. Look-ahead data may also include and not be limitedto the zone type where the lead locomotive is located, the location ofthe consist member, as well as any projections of energy, emissions,noise and power requirements of the lead locomotive and all consistmembers for each section or zone of the train's up and coming route

Again, the look-ahead route information is queried 1606 to determine ifthe engine may be needed within a second predetermined time 1606.Typically, the second predetermined time is longer than the firstpredetermined time. For example, the second predetermined time may beassociated with long periods of low speed operation or idling.

If there is too little time before the engine is required again, thenthe engine lubricating oil circulation is maintained operative 1607. Ifthere is sufficient time to turn off the lubricating oil circulationsystem, it is turned off 1608.

If idling is selected 1612 for engine deactivation, the next step 1613is to determine the power associated with the idle setting selected bythe engineer. The next step 1614 is to set engine alternator excitationcurrent so that the alternator output voltage is sufficiently below thecurrently selected DC bus voltage. The next step 1615 is to determinethe desired operating mode. Examples of operating modes include amaximum fuel efficiency mode, a minimum emissions mode, a combinationmode of good fuel efficiency and low emissions and an optimum enginelifetime mode. The next step 1616 is to use the engine's fuel map todetermine the engine idle rpms to achieve the operating mode selected instep 1615. Step 1617 is optional and is used to adjust excitationcurrent to move the operating point closer to the optimum value selectedin step 1615 while ensuring the output voltage remains well below theoperating DC bus voltage. Once the selected engine is deactivated byidling or turning it off (with or without the lubricating oilcirculating), then the algorithm returns to the main flow control chart1618.

FIG. 17 is an example of a flow chart for controlling activating anengine 1700 for a locomotive with multiple engines in parallel. Thefirst step 1701 is to determine if warm engines are available. In eithercase, the algorithm that selects the engines may consider the operatinghistory of the engines, as indicated by step 1702 or 1703, so as toavoid using some engines more than others and thereby approximatelybalancing the usage and maintenance period of the engines. Although lesspreferable than consulting an engine log, the selection algorithm may beengine selection by random number between one and the number ofavailable engines, which, over time, should tend to even out engineusage. The selection algorithm may be engine selection by rotation tothe next engine in an engine sequence which, over time, should also tendto even out engine usage. If there are no warm engines available, thenthe selected engine is preheated 1704.

Thereafter, the lubricating oil flow for the selected engine is turnedon 1705. The selected engine is then started 1706 and set to one of theavailable idle settings 1707 as selected by the engineer. The next step1708 is to set engine alternator excitation current so that thealternator output voltage is sufficiently below the currently selectedDC bus voltage. The next step 1709 is to determine the desired operatingmode. Examples of operating modes include a maximum fuel efficiencymode, a minimum emissions mode, a combination mode of good fuelefficiency and low emissions and an optimum engine lifetime mode. Thenext step 1710 is to use the engine's fuel map to determine the engineidle rpms to achieve the operating mode selected in step 1709. Step 1711is optional and is used to adjust excitation current to move theoperating point closer to the optimum value selected in step 1709 whileensuring the output voltage remains well below the operating DC busvoltage. Once the selected engine is activated, then the algorithmreturns to the main flow control chart 1712.

The following is an example of a more elaborate location-based,automated computer-controlled engine operating cycle for a multi-enginelocomotive, otherwise it is similar to the basic operating cycledescribed in FIG. 11. As can be appreciated, many of the steps can becarried out in different sequences and some of the steps may beoptional. FIG. 18 is another example of a main flow chart of automateddecision making for controlling the overall multi-engine selectionprocess and illustrates an automated cycle that begins 1800. The firststep 1801 in the decision cycle is to determine the train's locationalong its route at the time in question. This capability can be providedby, for example, a Global Positioning System (“GPS”) device, a radio, acell phone or by a transponder or mechanical locator situated along thetrack. The next step 1802 in the decision cycle is to determine thespeed of the locomotive. For a given notch power setting, thisdetermination allows the tractive effort, traction motor power, traction15 motor rpms, traction motor back emf, traction motor volts andtraction motor current to be computed. If the locomotive is idling andat rest, this step is trivial. The next step 1803 in the decision cycleis to determine the zone that the train is located in along its route.This can be done, for example, by using the train's determined locationand an on-board computer containing a detailed physical (2D or 3D asrequired) map of the train route and route requirements, to determinewhen the locomotive is in a zone where any of a number of emissions,noise restrictions and speed restrictions must be observed or wherecertain locomotive performance is required. An example of the latter maybe high acceleration such as, for example, exiting a station. The nextstep 1804 is to determine the location of the locomotive consist memberin the train, typically from the train location device in the leadlocomotive and from the knowledge of the number of cars that the consistmember is removed from the lead locomotive. If there is only onelocomotive, this step is trivial. In a long train where consist membersmay be at various locations, this step is included since consist memberscan be located in different operating zones. The next step 1805 is tolook ahead to project energy, emissions, noise and power requirements ofthe lead locomotive and all consist members for each section or zone ofthe train's up and coming route. In step 1806, the requirement foradditional engines currently deactivated is established from the dataacquired from step 1805. If additional engines are required, then thenumber of currently deactivated engines that must be activated isdetermined in step 1807. This engine activation step is described morefully in FIG. 17. The engine activation procedure is implemented in step1105 and the cycle then continues 1808. The cycle then continues 1809.As noted above, the locomotive operating mode is commonly set by thelocomotive's engineer. These are (1) a notch 1 to 8 power setting 1810,(2) an idle setting 1811, or (3) a dynamic braking setting 1812. Foreach of three power modes, it is possible that one or more engines maybe deactivated.

Deactivation means idling an engine so that it does not provide power tothe DC bus, or shutting off the engine. The deactivation of engines iscontrolled in step 1813. Step 1814 returns to the beginning of the maincontrol cycle.

FIG. 19 is a schematic of a preferred embodiment of multi-enginecurrent-based control feedback system with multiple engines in parallel.This schematic shows five engines 1901, each connected by mechanicalshafts 1902 to corresponding alternators 1903. Rectifiers 1904 areelectrically connected to the outputs of alternators 1903 to provide DCpower to a common DC bus 1905. In this embodiment, the output of the DCbus 1905 provides power to four traction motors 1906, each shown withload control apparatuses 1907. The electrical outputs of thealternator/rectifiers are connected in parallel with the DC bus 1905.The load controlled traction motors are also shown connected in parallelwith the DC bus 1905. This figure illustrates a preferred enginebalancing control feedback loop. An input command 1910 (for example aselected power level) is issued to a controller 1911. The outputcurrents from each engines' alternator/rectifier are measured by currentsensors 1912 which are monitored by the controller 1911. The controller1911 then uses the measured currents in a control feedback loop tomodify each engine's alternator 1903 excitation current or alternatorvoltage boost to bring each engine's power contribution into balancewith its pro rata portion of the total power to the DC bus. The controlfeedback loop is typically one of a number of well-known proportionalintegral differential (“PID”) control algorithms. The dotted lines 1920represent current feedback control circuit connections while the solidlines 1921 represent power distribution circuit connections.

FIG. 20 is a schematic of an alternate multi-engine current-basedcontrol feedback system with multiple engines in parallel. Thisschematic shows five engines 2001, each connected by mechanical shafts2002 to corresponding alternators 2003.

Rectifiers 2004 are electrically connected to the outputs of alternators2003 to provide DC power to a common DC bus 2005. In this embodiment,the output of the DC bus 2005 provides power to four traction motors2006, each shown with load control apparatuses 2007. The electricaloutputs of the alternator/rectifiers are connected in parallel with theDC bus 2005. The load controlled traction motors are also shownconnected in parallel with the DC bus 2005. This figure illustrates aless preferred engine balancing control feedback loop. An input command2010 (for example a selected power level) is issued to a controller2011. The output currents from each engines' alternator/rectifier aremeasured by current sensors 2012 which are monitored by the controller2011. The controller 2011 then uses the measured currents in a controlfeedback loop to modify each engine's 2001 speed (such for example bychanging the rate of fuel injection) to bring each engine's powercontribution into balance with its pro rata portion of the total powerto the DC bus. The control feedback loop is typically one of a number ofwell-known proportional integral differential (“PID”) controlalgorithms. The dotted lines 2020 represent current feedback controlcircuit connections while the solid lines 2021 represent powerdistribution circuit connections. This feedback control configuration isless preferable because (1) it is preferred to maintain the engine speedand power output at its optimum operating mode set point and (2) themechanical inertia of changing engine speeds tends to make the feedbackless responsive.

As can be appreciated, it is possible to use the measuredalternator/rectifier currents to adjust or modify a combination ofengine speed, engine alternator excitation current and, if available,alternator voltage boost to balance the power outputs of all the enginesto the DC bus.

Series Engine Configuration

FIG. 21 is a schematic circuit diagram of an alternate series connectedengine system for a multi-engine locomotive. Three-phase alternators2101 are shown along with their excitation coils 2102. The AC outputs ofeach alternator 2101 are connected to a rectifier circuit 2103. Theleftmost alternator/rectifier output is connected to the positive side2110 of a DC bus bar and to the middle alternator/rectifier byconnection 2104. The other output of the middle alternator/rectifier isconnected to the rightmost alternator/rectifier by connection 2105.Finally, the rightmost alternator/rectifier output is connected to thenegative side 2111 of the DC bus bar. The voltage V-bus applied to the10 DC bus is the sum of the individual alternator/rectifier outputs V1,V2 and V3. If an engine is turned off, or if the engine is on but withno excitation current, or if the engine is on but with not enoughexcitation current to produce a positive output voltage, then thevoltage output of that engine system is a small negative voltagecorresponding to the voltage drop across two conducting diodes. If theengine is on and has enough engine speed and excitation current toproduce a positive output voltage greater than the voltage drop acrossits rectifier diodes, then the engine system's output voltage ispositive and the engine system adds power to the DC bus. The amount ofpower that the engine system adds to the DC bus is the engine system'snet output voltage times the bus current.

FIG. 22 is a schematic block diagram of a propulsion system for amulti-engine locomotive with five engine systems in series. Thepropulsion system is comprised of five systems 2203 connected inparallel to a DC bus represented by a positive bus bar 2201 and anegative bus bar 2202. The mechanical shafts 2214 of engines 2204 drivealternators 2205 whose AC output is rectified by rectifier circuits 2206which are in turn connected to the DC bus. An auxiliary power supply2210 for the locomotive is shown connected to the DC bus by a voltageconversion apparatus 2211. In this example, four traction motors 2207are shown connected in parallel to the DC bus, each via an electricalenergy converter 2208 which is an inverter when traction motors 2207 areAC motors and a chopper circuit when traction motor 2207 are DC motors.An advantage of this configuration over that of the single enginelocomotive is that the five engines can have the same total power as thesingle engine but, as will be discussed subsequently, will allow moreefficient fuel management in many situations such as transition fromhigh speed to low speed or, in the case of a yard switcher locomotivefor example, transition from high speed to low speed at high power.Another advantage of this configuration over that of the single enginelocomotive is the greater ease of serviceability including removal andreplacement of smaller engines over that of a single large engine.

FIG. 23 is a schematic circuit diagram of a propulsion system for amulti-engine locomotive with five engine systems 2302 in series whichcorresponds to the block diagram of FIG. 22. The engines are all shownwith wound rotor alternators 2302 and rectifiers 2303 although theengine systems may be of different sizes and types and the alternatorsmay be permanent magnet machines, asynchronous alternators such asinduction alternators, DC generators, or switched reluctance generators.The output voltage from each engine system may be measured by its ownoutput voltage sensor (not shown). These five prime engine systemsprovide power to a DC bus shown by conductors 2305 and 2306. The circuitof FIG. 23 also includes a propulsion system 2307 shown here with fourtraction motors, an auxiliary power system 2308 with its voltage controlcircuit 2309. The circuit also includes a resistive grid 2310 and switch2311 that provides a dynamic braking capability. With its engine systemsconnected in series to the DC bus, the voltage on the DC bus is the sumof the net output voltages of each of the five engine systems asdescribed in FIG. 21. This locomotive power circuit is an example of amulti-engine locomotive with regenerative braking capability that couldbe used, for example, as a road switcher. A similar electricalarchitecture for a series-connected multi-engine power system wasdisclosed previously in U.S. Provisional patent application entitled“Marine Power Train Architecture” by Donnelly and Watson filed Oct. 24,2006.

Control and Balancing of Multi-Engine in Series

In series configuration, the output voltage of each engine systemproviding power to the DC bus is added to produce the voltage measuredon the DC bus. Thus a measurement of the output voltage of an enginesystem is an accurate measurement of the engine system's power to the DCbus and is the preferred method of determining engine system's outputpower. An engine system's output power is its output voltage times theDC bus current. If only DC bus voltage is measured, an engine system'srelative output power compared to the other engines providing power canstill be obtained by each engine system's measured output voltage the Inseries configuration, the general method of ensuring the desired enginesystem output power is then:

-   -   set the desired DC bus voltage or bus voltage range and measure        the DC bus voltage; or set the desired DC bus current or bus        current range and measure the DC bus current    -   for each engine system, measure its output voltage and use this        to determine its output power (its voltage times DC bus current)        or output power relative to the other engines (relative output        voltages are relative output powers since current is the same)    -   if the engine system is not outputting the desired power or        desired power relative to the other engines, adjust an engine        system electrical or mechanical parameter to produce desired        engine system output voltage and hence power

FIG. 24 is an overview flowchart showing the primary steps in amulti-engine control loop with multiple engines in series. In FIG. 24,step 2401 determines all the inputs required to set locomotive powerrequirements, select engines, set the DC bus voltage and/or current, setthe power and speed of the engines, balance the flow of power from theengines and adjust the load if load control is available. Step 2402 iswhere the power requirements for the locomotive are establisheddepending on a number of variables determined in step 2401. In step2403, engines are selected. This includes the number of engines, thespecific engines, which engines need to be activated for future use andwhich engines can be deactivated. In step 2404, the DC bus voltageand/or current is selected. A specific operating voltage and/or currentis selected for the load control embodiment. The DC bus voltage orcurrent is not determined in the embodiment which has no load control.In step 2405, the power and speed (rpms) of each engine is set based onthe power requirements and engine operating mode determined in step2402. In step 2406, the power outputs of all engines are measured bymeasuring the output voltage of each engine system. In this step, thepower outputs are balanced so that each engine is contributing its prorata share of the output power. This step is may be accomplished byadjusting engine speed (rpms) and/or alternator excitation current toachieve the required engine system power output. Finally, in step 2407,the load is adjusted if load control is used. In this step the power tothe load is adjusted to equal the power available from the DC bus. Thisis accomplished for example by choppers which regulate DC tractionmotors or inverters which regulate AC motors.

FIG. 25 is an example of a main flow chart of automated decision makingfor controlling the overall multi-engine selection operating andbalancing process with multiple engines in series. This cycle ofdecisions can be executed continuously (for example every millisecond)or intermittently (for example every 1 second) or at intervals inbetween by a predetermined computer program or by a computer programthat adapts, such as for example, a program based on neural networkprinciples. As can be appreciated, many of the steps can be carried outin different sequences and some of the steps may be optional.

As is common practice, the choices of applying traction power, applyingdynamic braking or operating the locomotive at idle to supply auxiliarypower are made by the locomotive engineer or operator utilizing controlsin the cab, or via a remote-control or equivalent system when, forexample, in a switch yard.

As shown in the example of FIG. 25, an automated cycle begins 2500. Thefirst step 2502 is to estimate the power requirements and operating modeof the locomotive. In step 2503, the requirement for additional enginescurrently deactivated is established from step 2502. If additionalengines are required, then the number of currently deactivated enginesthat must be activated is determined in step 2504. This engineactivation step is described more fully in FIG. 31. The engineactivation procedure is implemented in step 2505 and the cycle thencontinues 2506. As noted above, the locomotive operating mode iscommonly set by the locomotive's engineer. These are (1) a notch 1 to 8power setting 2507, (2) an idle setting 2508, or (3) a dynamic brakingsetting 2509. For each of three power modes, it is possible that one ormore engines may be deactivated. Deactivation means idling an engine sothat it does not provide power to the DC bus, or shutting off theengine. The deactivation of engines is controlled in step 2510. Step2511 returns to the beginning of the main control cycle.

FIG. 26 is an example of a flow chart for selecting and configuringengines for any of the notch 1 to 8 power settings 2600 with no loadcontrol with multiple engines connected in electrical series. FIG. 26shows an example of a flow chart for automated selection andconfiguration of engines for any of the notch 1 to 8 power settings2600.

This figure illustrates the process for a locomotive that does not havean independent means of load control. That is, the traction motors maybe able to consume more power than the engines can provide, depending onengine alternator excitation settings and traction motor volts which area function of locomotive speed. The first step 2601 is to determine thepower associated with the notch number selected by the engineer and todetermine the locomotive speed. The latter can be determined from anumber of well-known means such as for example by a speedometer, bymeasuring axle rpms, by using a radar system and the like. Each notchnumber is typically associated with a predetermined power level at eachlocomotive speed, notch 1 being the lowest power setting and notch 8being the highest power setting. As can be appreciated, the power levelassociated with each notch setting can be varied from time to time byreprogramming an on-board computer. The next step 2602 is to determinethe desired engine operating mode. Examples of operating modes, whichwere previously illustrated in FIGS. 3 and 4, include a maximum fuelefficiency mode, a minimum emissions mode, a combination mode of goodfuel efficiency and low emissions, an optimum engine lifetime mode, anda maximum power mode. The choice may be determined by the engineer or bya predetermined algorithm based on data from the locomotive's routelocation and requirements for the zone in which the locomotive orconsist member is operating.

The next step 2603 is to determine the number of engines operative toprovide power to the DC bus, Step 2603 may be carried out by analgorithm controlled by an on-board computer. It may also be based on apredetermined lookup table which associates each notch, each appropriatelocomotive speed range and its various operating modes with an operatingpoint such as described in FIGS. 3 and 4. It is also possible that, atsome notch settings, all but one of the engines can be set at or nearthe selected operating points and the all but one engine can be used tobalance out the total selected notch power by being set at a non-optimumoperating point. Alternately, the all but one engine can be used tobalance out the total selected notch power by using its alternatorvoltage boost capability (if available) to independently control itsoutput voltage and thus can also be set at a its optimum operatingpoint. Either of these methods can provide a degree of control overpower output and operating points that is not available with a singlelarge engine. A single large engine can be set at only one power andspeed setting and often has to trade off better fuel economy for loweremissions. In a multiple engine locomotive, all but one of thepower-producing engines (or all engines when alternator boost isavailable) can be tuned to optimize power, fuel consumption andemissions and often the one engine can be operated near its optimumoperating point. In the step 2603 where all the engines are the same,selection of the number of engines operative to provide power to the DCbus is typically done by dividing the power requirement determined instep 2601 by the power rating of the engines and rounding the resultingnumber upwards. In the step 2603 where all the engines are the same andin series, selection of the number of engines operative to provide powerto the DC bus can also be done by dividing the desired DC bus voltagedetermined in step 2601 by the output voltage rating of the engines androunding the resulting number upwards. In the case where there areengines of differing power ratings, the selection algorithm may be moreinvolved so as to balance the power contribution from each engine. Ineither case, the algorithm that selects the number of engines mayconsider the operating history of the engines, as indicated by step2604, so as to avoid using some engines more than others and therebyapproximately balancing the usage and maintenance period of the engines.

An engine log typically contains information on engine usage (hours,fuel consumption, lubricant consumption, total rpms, megawatt-hours,hours in idle modes, hours in the various notch settings and hours indynamic braking and the like) and maintenance history. Although lesspreferable than consulting an engine log, the selection algorithm may beengine selection by a random number between one and the number ofavailable engines, which, over time, should tend to even out engineusage. The selection algorithm may be engine selection by rotation tothe next engine in an engine sequence which, over time, should also tendto even out engine usage. In the next step 2605, a selected engine mayneed to be derated. For example, the selected engine may have one ormore cylinders operating at less than optimum rating, the engine'scontrol system may automatically derate the engine to a lower powerafter a specified time period of operating at a higher-than-normal powerrating or any number of other well-known reasons for derating engineperformance. If an engine is required to be derated 2606, then theprocedure returns to step 2603 to re-select the number of engines sincethe derated engine may require an additional engine to provide therequested power. In the next step 2607, the engines not selected forproviding power to the DC bus are identified for deactivation and may beselected to be idled or shut down to be deactivated. This deactivationprocedure is controlled in step 2513 of the main flow chart (FIG. 25)and fully described in FIG. 30.

In the next step 2608, the desired bus voltage and/or current range forthe selected notch setting is selected and either or both of bus voltageand bus current are measured. As the power consumed by the load(traction motors) increases beyond the optimum engine power capacity,the engine speeds will begin to decrease. In step 2609, typically a loadvariable such as total load current or torque is measured and used in afirst control feedback loop to increase engine speeds by decreasingtheir alternator excitation currents which tends to decrease alternatoroutput voltages. As this occurs for all the engines, the DC bus voltagedrops, reducing the power to the load by reducing motor voltage untilthe total engine power output matches the power required by the load.This is a stable feedback process commonly carried out automatically foreach engine by one of a number of well-known proportional integraldifferential (“PID”) control algorithms. Thus, the DC bus voltage may behighly variable, typically ranging from near zero volts to well over1,000 volts.

The next step 2610 begins an internal control loop 2650 for each engineto obtain a balanced power flow from each engine. Each engine has a fuelmap which is typically a plot of engine power or torque versus enginerpms for various contours of constant specific fuel consumption, and anemissions map which is typically a plot of engine power or torque versusengine rpms for various contours of constant specific NOx emissions. Ascan be appreciated, there may be additional emissions maps forhydrocarbons and particulate matter and the like. In step 2611, the rpmsof the selected 10 engine is determined so as to produce the requiredpower at the specific fuel consumption and emissions rate correspondingto the operating mode selected in step 2602. In step 2612, theexcitation current for the alternator of each engine is selected toprovide an alternator output voltage to fall within the range of the DCbus voltage and/or bus current measured in step 2608. When available,the amount of alternator boost may also be used to generate outputvoltage to fall within the range of the DC bus voltage measured in step2608. This latter capability may be useful for example when an engine isderated or when an engine is operated at a lower power and rpm so thatthe engine may continue to supply power to the DC bus by havingindependent control over its alternator output voltage.

Step 2613 is a step where the net output voltage of each engine systemis measured at the output of each alternator's rectifier circuit. Thisvoltage times the DC bus current is a direct measure of the powerflowing from the selected engine. An engine system output voltagemeasurement is a sensitive and direct measure of power output of theengine system to the DC bus for the series engine configuration. In theseries engine configuration, if the bus current is not known, the enginesystem output voltages are a relative measurement of power output of theengine system to the DC bus since the sum of all the series connectedengine system output voltages equals the bus voltage (see FIG. 21). Themeasured voltage is used in a second control feedback loop to modify theengine's alternator excitation current to bring the engine's powercontribution into balance with its pro rata portion of the total powerto the DC bus. This feedback and balancing can be done if the absolutepower or relative power of each engine is so measured. In the case whereall engines are set to the same output power, each engine is balanced todeliver the same amount of power as the other engines to within apredetermined tolerance, preferably in the range of about ±5%. Thissecond control feedback loop is designed to be a stable feedback processcommonly carried out automatically for each engine by one of a number ofwell-known proportional integral differential (“PID”) controlalgorithms.

The next step 2614 is executed for all engines after all engines havebeen balanced via internal control loop 2650. In step 2615, the totalpower from all engines to the DC bus is determined, preferably bymeasuring the voltage at the output of each engine system andmultiplying the sum by the measured DC bus current and less preferablyby measuring the voltage at the output of each engine system andmultiplying the sum by an estimated DC bus current (for example bymeasuring the current flowing to each traction motor, auxiliary powersupply and other sources of power draw and summing these).

Once the allocation of power to the traction motors is determined 2615,the algorithm proceeds to the engine deactivation control loop 2616.

FIG. 27 is an example of a flow chart for selecting and configuringengines for any of the notch 1 to 8 power settings 2700 with loadcontrol with multiple engines in series. This figure illustrates theprocess for a locomotive that has an independent means of load controlwhich is a preferred embodiment. That is, the power distributed to thetraction motors is controlled independently such that the total powerdistributed to the load is controlled to match the power available fromthe engines. This may be done for example by using one or more choppersat the output of the DC bus to DC traction motors, or by using one ormore inverters at the output of the DC bus to AC traction motors. Thefirst step 2701 is to determine the power associated with the notchnumber selected by the engineer and to determine the locomotive speed.As can be appreciated, the power level associated with each notchsetting can be varied from time to time by reprogramming an on-boardcomputer. The next step 2702 is to determine the desired engineoperating mode. Examples of operating modes are described in thediscussion of FIG. 26. The choice may be determined by the engineer orby a predetermined algorithm based on data from the locomotive's routelocation and requirements for the zone in which the locomotive orconsist member is operating.

The next step 2703 is to determine the number of engines operative toprovide power to the DC bus, Step 2703 may be carried out by analgorithm controlled by an onboard computer. It may also be based on apredetermined lookup table which associates each notch, each appropriatelocomotive speed range and its various operating modes with an operatingpoint such as described in FIGS. 3 and 4. It is also possible asdescribed previously that, at some notch settings, all but one of theengines can be set at or near the selected operating points and oneengine can be used to balance out the total selected notch power bybeing set at a non-optimum operating point (also use can be made ofalternator boost as described in step 2603 of FIG. 26). In the step 2703where all the engines are the same, selection of the number of enginesoperative to provide power to the DC bus is typically done by dividingthe power requirement determined in step 2701 by the power rating of theengines and rounding the resulting number upwards.

In the step 2703 where all the engines are the same and in series,selection of the number of engines operative to provide power to the DCbus can also be done by dividing the desired DC bus voltage determinedin step 2701 by the output voltage rating of the engines and roundingthe resulting number upwards. In the case where there are engines ofdiffering power ratings, the selection algorithm may be more involved soas to balance the power contribution from each engine. In either case,the algorithm that selects the number of engines may consider theoperating history of the engines, as indicated by step 2704, so as toavoid using some engines more than others and thereby approximatelybalancing the usage and maintenance period of the engines. Although lesspreferable than consulting an engine log, the selection algorithm may beengine selection by random number between one and the number ofavailable engines, which, over time, should tend to even out engineusage. The selection algorithm may be engine selection by rotation tothe next engine in an engine sequence which, over time, should also tendto even out engine usage. In the next step 2705, a selected engine mayneed to be derated. If an engine is required to be derated 2706, thenthe procedure returns to step 2703 to re-select the number of enginessince the derated engine may require an additional engine to provide therequired notch power. In the next step 2707, the engines not selectedfor providing power to the DC bus are identified for deactivation andmay be selected to be idled or shut down to be deactivated. Thisdeactivation procedure is controlled in step 2513 of the main flow chart(FIG. 25) and fully described in FIG. 30.

In the preferred load control embodiment, the next step 2708 is to setthe desired nominal value and range for the DC bus voltage and/orcurrent. The range is preferably ±75 volts from the nominal DC busvoltage, more preferably ±50 volts from the nominal DC bus voltage, andmost preferably ±25 volts from the nominal DC bus voltage. This voltagemay be set at a different predetermined nominal value for each notchsetting, or at a predetermined nominal value for a range of notchsettings, or at the same predetermined nominal value for all notchsettings.

The next step 2709 begins an internal control loop 2750 for each engineto obtain a balanced power flow from each engine. Each engine has a fuelmap and an emissions map or maps. In step 2710, the rpms of the selectedengine is determined so as to produce the required power at the specificfuel consumption and emissions rate corresponding to the operating modeselected in step 2702. In step 2711, the excitation current for thealternator of each engine is selected to provide an alternator outputvoltage to match the selected DC bus voltage and/or bus current. Step2712 is a step where the net output voltage of each engine system ismeasured at the output of each alternator's rectifier circuit. Thisvoltage times the DC bus current is a direct measure of the powerflowing from the selected engine. An engine system output voltagemeasurement is a sensitive and direct measure of power output of theengine system to the DC bus for the series engine configuration. In theseries engine configuration, if the bus current is not known, the enginesystem output voltages are a relative measurement of power output of theengine system to the DC bus since the sum of all the series connectedengine system output voltages equals the bus voltage (see FIG. 21).

The measured voltage is used in a second control feedback loop to modifythe engine's alternator excitation current to bring the engine's powercontribution into balance with its pro rata portion of the total powerto the DC bus. This feedback and balancing can be done if the absolutepower or relative power of each engine is so measured. In the case whereall engines are set to the same output power, each engine is balanced todeliver the same amount of power as the other engines within apredetermined tolerance, preferably about ±5%. This control feedbackloop is designed to be a stable feedback process commonly carried outautomatically for each engine by one of a number of well-knownproportional integral differential (“PID”) control algorithms.

The next step 2713 is executed for all engines after all engines havebeen set via internal control loop 2750. In step 2714, the total powerfrom all engines to the DC bus is determined, preferably by measuringthe voltage at the output of each engine system and multiplying the sumby the measured DC bus current and less preferably by measuring thevoltage at the output of each engine system and multiplying the sum byan estimated DC bus current (for example by measuring the currentflowing to each traction motor, auxiliary power supply and other sourcesof power draw and summing these). If the total power is too low 2715 toprovide the required power to the traction motors, then the power toselected traction motors is reduced 2716 to the amount of poweravailable from the DC bus. This power reduction can be made equal to alltraction motors or can be allocated based on an algorithm that considerseach powered wheel-set separately. The latter is an available strategyif each traction motor has its own power control apparatus (such as achopper circuit for each DC traction motor or an inverter for each ACtraction motor). Power may be selectively reduced for example on theleading wheel set in wet conditions. Once the allocation of power to thetraction motors is determined 2714, the algorithm proceeds to the enginedeactivation control loop 2717.

In a locomotive without an independent means of load control, if theengine power is too low to provide the required power to the tractionmotors, then (1) the engine power may be adjusted upwards or (2) thepower to traction motors may be reduced by lowering the alternatorexcitation current until the alternator output voltage matches thetraction motor voltage. In the preferred multi-engine locomotive controlmeans of the present invention, if the total power from the engines istoo low to provide the required power to the traction motors, thenpreferably the power to traction motors is reduced by a small amount toequal the power available. Alternately, another engine may be added toprovide the necessary power in all but the highest notch setting. At thehighest notch setting, it is still possible to increase the power outputof one or more engines for periodic overloads. Thus, the control andbalancing of output power from the engines can always be separatelyadjusted from the load power requirements of the traction motors bycontrolling a predetermined maximum load on the engines.

FIG. 28 shows an example of a flow chart for automated selection andconfiguration of multiple engines in series for any of number of idlesettings 2800. Typically, a locomotive has a high idle and a low idlesetting. The latter may be used, for example, to minimize fuelconsumption for long periods of idle. This figure illustrates theprocess for a locomotive that has an independent means of load controlsimilar to that described in FIG. 27, which is a preferred embodiment.As can be appreciated, the process can be modified for a locomotive thatdoes not have an independent means of load control such as described inFIG. 26. The next step 2802 is to determine the desired engine operatingmode. Examples of operating modes are described in the discussion ofFIG. 26. The choice may be determined by the engineer or by apredetermined algorithm based on data from the locomotive's routelocation and requirements for the zone in which the locomotive orconsist member is operating. The next step 2803 is to determine thenumber of engines operative to idle and provide power to the DC bus.Step 2803 may be carried out by an algorithm controlled by an on-boardcomputer. It may also be based on a predetermined lookup table whichassociates each idle setting and its various operating modes with anoperating point such as described in FIGS. 3 and 4. It is also possiblethat, at some idle settings, all but one of the engines can be set at ornear the selected operating points and the all but one engine can beused to balance out the total selected idle power by being set at anon-optimum operating point. Alternately, the all but one engine can beused to balance out the total selected notch power by using itsalternator voltage boost, if available, to independently control itsoutput voltage and thus can also be set at a its optimum operatingpoint. This provides a degree of control over power output and operatingpoints that is not available with a single large engine. In the step2803 where all the engines are the same, selection of the number ofengines operative to provide power to the DC bus is typically done bydividing the power requirement determined in step 2801 by the powerrating of the engines and rounding the resulting number upwards. In thestep 2803 where all the engines are the same and in series, selection ofthe number of engines operative to provide power to the DC bus can alsobe done by dividing the desired DC bus voltage determined in step 2801by the output voltage rating of the engines and rounding the resultingnumber upwards.

In the case where there are engines of differing power ratings, theselection algorithm may be more involved so as to balance the powercontribution from each engine. In either case, the algorithm thatselects the number of engines may consider the operating history of theengines, as indicated by step 2804, so as to avoid using some enginesmore than others and thereby approximately balancing the usage andmaintenance period of the engines. Although less preferable thanconsulting an engine log, the selection algorithm may be engineselection by random number between one and the number of availableengines, which, over time, should tend to even out engine usage. Theselection algorithm may be engine selection by rotation to the nextengine in an engine sequence which, over time, should also tend to evenout engine usage. In the next step 2805, a selected engine may need tobe derated. If an engine is required to be derated 2806, then theprocedure returns to step 2803 to re-select the number of engines sincethe derated engine may require an additional engine to provide therequired idle power. In the next step 2807, the engines not selected forproviding power to the DC bus are identified for deactivation and may beselected to be idled but not providing power to the DC bus, or shut downto be deactivated. This deactivation procedure is controlled in step2513 of the main flow chart (FIG. 25) and fully described in FIG. 30.

In the preferred load control embodiment, the next step 2808 is to setthe desired nominal value and range for the DC bus voltage and/orcurrent. The range is preferably ±75 volts from the nominal DC busvoltage, more preferably ±50 volts from the nominal DC bus voltage, andmost preferably ±25 volts from the nominal DC bus voltage. This voltagemay be set at a different predetermined value for each idle setting butmost preferably at the same predetermined value for all idle settings.

The next step 2809 begins an internal control loop 2850 for each engineto obtain a balanced power flow from each engine. Each engine has a fuelmap and an emissions map or maps. In step 2810, the rpms of the selectedengine is determined so as to produce the required power at the specificfuel consumption and emissions rate corresponding to the operating modeselected in step 2802. In step 2811, the excitation current for thealternator of each engine is selected to provide an alternator outputvoltage to match the selected DC bus voltage. When available, the amountof alternator boost may also be used to generate output voltage to fallwithin the range of the DC bus voltage and/or bus current measured instep 2808. Step 2812 is a step where the net output voltage of eachengine system is measured at the output of each alternator's rectifiercircuit. This voltage times the DC bus current is a direct measure ofthe power flowing from the selected engine. An engine system outputvoltage measurement is a sensitive and direct measure of power output ofthe engine system to the DC bus for the series engine configuration. Inthe series engine configuration, if the bus current is not known, theengine system output voltages are a relative measurement of power outputof the engine system to the DC bus since the sum of all the seriesconnected engine system output voltages equals the bus voltage (see FIG.21).

The measured voltage is used in a second control feedback loop to modifythe engine's alternator excitation current to bring the engine's powercontribution into balance with its pro rata portion of the total powerto the DC bus. This feedback and balancing can be done if the absolutepower or relative power of each engine is so measured. In the case whereall engines are set to the same output power, each engine is balanced todeliver the same amount of power as the other engines within apredetermined tolerance, preferably about ±5%. This control feedbackloop is designed to be a stable feedback process commonly carried outautomatically for each engine by one of a number of well-knownproportional integral differential (“PID”) control algorithms.

The next step 2813 is executed for all engines after all engines havebeen set via internal control loop 2850. In step 2814, the total powerfrom all engines to the DC bus is determined, preferably by measuringthe voltage at the output of each engine system and multiplying the sumby the measured DC bus current and less preferably by measuring thevoltage at the output of each engine system and multiplying the sum byan estimated DC bus current (for example by measuring the currentflowing to each traction motor, auxiliary power supply and other sourcesof power draw and summing these). If the total power is too low 2815 toprovide the required power to provide for the idling locomotive, thenthe idle setting may be changed 2816 to a higher setting, the powerprovided at the selected idle setting may be increased or the powerrequired by the locomotive may be reduced. A reduction in the hotelpower required for a passenger train idling in a station is an exampleof the latter. Once the allocation of power to the auxiliary power needsis set to match the available power from all the idled butpower-contributing engines, the algorithm proceeds to the enginedeactivation control loop 2817.

FIG. 29 shows an example of a flow chart for automated selection andconfiguration of multiple engines in series for dynamic braking 2900.This figure illustrates the process for a locomotive that has anindependent means of load control similar to that described in FIG. 26,which is a preferred embodiment. It is understood that the tractionmotors act as generators during dynamic braking and can provide powerback to flow to the DC bus. As can be appreciated, the power levelprovided by dynamic braking can be controlled by power control circuitsassociated with the traction motors.

The first step 2901 is to estimate the power required by the locomotiveduring the projected period that the locomotive is expected to be indynamic braking mode. This can be accomplished using the informationavailable on the locomotive's location along its route and its projectedroute. The next step 2902 is to determine whether the projected powerrequirements can be met by dynamic braking or whether some engine powerwill also be required. If all the required power can be supplied bydynamic braking 2903, then no engines need be engaged to provide powerto the DC bus. This situation can arise, for example, if the train istraveling down a lengthy grade. In this case, the power from dynamicbraking may exceed the auxiliary requirements of the locomotive and someof the dynamic braking energy may be switched to a resistive grid fordissipation. As can be appreciated, substantial auxiliary power may berequired to operate the traction motor blowers that provide coolingduring high current operation typical of dynamic braking and this mayrequire some engine power to the DC bus. In the case where dynamicbraking is intermittent or only operative for a short period, enginesmay be required to provide additional power to the DC bus. If enginesare required, they may be operated in an idle setting or a notch powersetting, depending on the locomotive's requirements. For example, a roadswitcher may not require substantial auxiliary power during braking buta commuter train with a large hotel load, may require more power than isavailable through dynamic braking alone. If engines are required, thenext step 2904 is to set the output power required by the engines.

The next step 2905 is to determine the desired operating mode of theengines. Examples of operating modes include a maximum fuel efficiencymode, a minimum emissions mode, a combination mode of good fuelefficiency and low emissions and an optimum engine lifetime mode. Thechoice may be determined by the engineer or by a predetermined algorithmbased on data from the locomotive's route location and requirements forthe zone in which the locomotive or consist member is operating. Thenext step 2906 is to determine the number of engines operative toprovide power to the DC bus. This step, which is essentially the same asthat described in step 2604 of FIGS. 26 and 2704 in FIG. 27 is typicallydone by dividing the power requirement determined in step 2904 by thepower rating of the engines and rounding the resulting number upwards inthe case where all the engines are the same. In the step 2904 where allthe engines are the same and in series, selection of the number ofengines operative to provide power to the DC bus can also be done bydividing the desired DC bus voltage determined in step 2901 by theoutput voltage rating of the engines and rounding the resulting numberupwards. In the case where there are engines of differing power ratings,the selection algorithm may be more involved so as to balance the powercontribution from each engine. In either case, the algorithm thatselects the number of engines may consider the operating history of theengines, as indicated by step 2907, so as to avoid using some enginesmore than others and thereby approximately balancing the usage andmaintenance period of the engines. Although less preferable thanconsulting an engine log, the selection algorithm may be engineselection by random number between one and the number of availableengines, which, over time, should tend to even out engine usage. Theselection algorithm may be engine selection by rotation to the nextengine in an engine sequence which, over time, should also tend to evenout engine usage.

In the next step 2908, a selected engine may need to be derated. If anengine is required to be derated 2909, then the procedure returns tostep 2906 to re-select the number of engines since the derated enginemay require an additional engine to provide the required idle power. Inthe next step 2910, the engines not selected for providing power to theDC bus are identified for deactivation and may be selected to be idledbut not providing power to the DC bus, or shut down to be deactivated.This deactivation procedure is controlled in step 2513 of the main flowchart (FIG. 25) and fully described in FIG. 16.

In the preferred load control embodiment, the next step 2911 is to setthe desired nominal value and range for the DC bus voltage and/orcurrent. The range is preferably ±75 volts from the nominal DC busvoltage, more preferably ±50 volts from the nominal DC bus voltage, andmost preferably ±25 volts from the nominal DC bus voltage. This voltagemay be set at a different predetermined value depending on the amount ofpower estimated from dynamic braking and from the power that can besupplied by the engines. It also depends whether the engines willprovide power from an idle setting (such as for example high idle) orfrom a notch power setting.

The next step 2912 begins an internal control loop 2950 for each engineto obtain a balanced power flow from each engine. Each engine has a fuelmap and an emissions map or maps. In step 2913, the rpms of the selectedengine is determined so as to produce the required power at the specificfuel consumption and emissions rate corresponding to the operating modeselected in step 2905. In step 2914, the excitation current for thealternator of each engine is selected to provide an alternator outputvoltage to match the selected DC bus voltage and/or bus current. Step2915 is a step where the net output voltage of each engine system ismeasured at the output of each alternator's rectifier circuit. Thisvoltage times the DC bus current is a direct measure of the powerflowing from the selected engine. An engine system output voltagemeasurement is a sensitive and direct measure of power output of theengine system to the DC bus for the series engine configuration. In theseries engine configuration, if the bus current is not known, the enginesystem output voltages are a relative measurement of power output of theengine system to the DC bus since the sum of all the series connectedengine system output voltages equals the bus voltage (see FIG. 21). Themeasured voltage is used in a second control feedback loop to modify theengine's alternator excitation current to bring the engine's powercontribution into balance with its pro rata portion of the total powerto the DC bus. This feedback and balancing can be done if the absolutepower or relative power of each engine is so measured. In the case whereall engines are set to the same output power, each engine is balanced todeliver the same amount of power as the other engines within apredetermined tolerance, preferably about ±5%. This control feedbackloop is designed to be a stable feedback process commonly carried outautomatically for each engine by one of a number of well-knownproportional integral differential (“PID”) control algorithms.

The next step 2916 is executed for all engines after all engines havebeen set via internal control loop 2950. In step 2917, the total powerfrom all selected engines is determined, preferably by measuring thevoltage at the output of each engine system and multiplying the sum bythe measured DC bus current and less preferably by measuring the voltageat the output of each engine system and multiplying the sum by anestimated DC bus current (for example by measuring the current flowingto each traction motor, auxiliary power supply and other sources ofpower draw and summing these). The power available from dynamic brakingis determined in step 2918. The total power available to the locomotiveor consist member is determined in step 2919 which is the sum of thepower to the DC bus from the engines and dynamic braking. If the totalpower is too low 2920 to provide the required power for the brakinglocomotive, then the power provided by the selected engines may beincreased 2921 or the power required by the locomotive may be reduced2921. Once the allocation of power to the auxiliary power needs is setto match the available power from the selected engines and dynamicbraking, the algorithm proceeds to the engine deactivation control loop2922.

FIG. 30 is an example of a flow chart for controlling enginedeactivation 3000 for a locomotive with multiple engines in series.Deactivation means idling an engine so that it does not provide power tothe DC bus; or shutting off the engine.

In step 3001, an engine is selected to be idled or shut down fordeactivation. If shut down is selected 3002, then the look-ahead routeinformation is queried 3003 to determine if the engine may be neededwithin a first predetermined time 3004 in which case the shut downselection would not be efficient. If there is too little time before theengine is required again, then the idle mode for deactivation isautomatically selected 3012. If there is sufficient time to shut downthe engine, then the engine is selected to be turned off 3005.

Again, the look-ahead route information is queried 3006 to determine ifthe engine may be needed within a second predetermined time 3006.Typically, the second predetermined time is longer than the firstpredetermined time. For example, the second predetermined time may beassociated with long periods of low speed operation or idling.

If there is too little time before the engine is required again, thenthe engine lubricating oil circulation is maintained operative 3007. Ifthere is sufficient time to turn off the lubricating oil circulationsystem, it is turned off 3008. If idling is selected 3012 for enginedeactivation, the next step 3013 is to determine the power associatedwith the idle setting selected by the engineer. The next step 3014 is toset engine alternator excitation current so that the alternator outputis approximately zero so no power is supplied to the DC bus. The nextstep 3015 is to determine the desired operating mode. Examples ofoperating modes include a maximum fuel efficiency mode, a minimumemissions mode, a combination mode of good fuel efficiency and lowemissions and an optimum engine lifetime mode.

The next step 3016 is to use the engine's fuel map to determine theengine idle rpms to achieve the operating mode selected in step 3015.Step 3017 is optional and is used to adjust excitation current to movethe operating point closer to the optimum value selected in step 3015while ensuring the engine system output voltage remains approximatelyzero so no power is supplied to DC bus. Once the selected engine isdeactivated by idling or turning it off (with or without the lubricatingoil circulating), then the algorithm returns to the main flow controlchart 3018.

FIG. 31 is an example of a flow chart for controlling activating anengine 3100 for a locomotive with multiple engines in series. The firststep 3101 is to determine if warm engines are available. In either case,the algorithm that selects the engines may consider the operatinghistory of the engines, as indicated by step 3102 or 3103, so as toavoid using some engines more than others and thereby approximatelybalancing the usage and maintenance period of the engines. Although lesspreferable than consulting an engine log, the selection algorithm may beengine selection by random number between one and the number ofavailable engines, which, over time, should tend to even out engineusage. The selection algorithm may be engine selection by rotation tothe next engine in an engine sequence which, over time, should also tendto even out engine usage. If there are no warm engines available, thenthe selected engine is preheated 3104.

Thereafter, the lubricating oil flow for the selected engine is turnedon 3105. The selected engine is then started 3106 and set to one of theavailable idle settings 3107 as selected by the engineer. The next step3108 is to set engine alternator excitation current so that the enginesystem output voltage remains approximately zero so no power is suppliedto DC bus. The next step 3109 is to determine the desired operatingmode.

Examples of operating modes include a maximum fuel efficiency mode, aminimum emissions mode, a combination mode of good fuel efficiency andlow emissions and an optimum engine lifetime mode. The next step 3110 isto use the engine's fuel map to determine the engine idle rpms toachieve the operating mode selected in step 3109. Step 25 3111 isoptional and is used to adjust excitation current to move the operatingpoint closer to the optimum value selected in step 3109 while ensuringthe engine system output voltage remains approximately zero so no poweris supplied to DC bus. Once the selected engine is activated, then thealgorithm returns to the main flow control chart 3112.

The following is an example of a more elaborate location-based automatedcomputer-controlled engine operating cycle for a multi-enginelocomotive, otherwise it is similar to the basic operating cycledescribed in FIG. 24. As can be appreciated, many of the steps can becarried out in different sequences and some of the steps may beoptional. FIG. 32 is another example of a main flow chart of automateddecision making for controlling the overall multi-engine selectionprocess and illustrates an automated cycle that begins 3200. The firststep 3201 in the decision cycle is to determine the train's locationalong its route at the time in question. This capability can be providedby, for example, a Global Positioning System (“GPS”) device, a radio, acell phone or by a transponder or mechanical locator situated along thetrack. The next step 3202 in the decision cycle is to determine thespeed of the locomotive. For a given notch power setting, thisdetermination allows the tractive effort, traction motor power, tractionmotor rpms, traction motor back emf, traction motor volts and tractionmotor current to be computed. If the locomotive is idling and at rest,this step is trivial. The next step 3203 in the decision cycle is todetermine the zone that the train is located in along its route. Thiscan be done, for example, by using the train's determined location andan on-board computer containing a detailed physical (2D or 3D asrequired) map of the train route and route requirements, to determinewhen the locomotive is in a zone where any of a number of emissions,noise restrictions and speed restrictions must be observed or wherecertain locomotive performance is required. An example of the latter maybe high acceleration such as, for example, exiting a station. The nextstep 3204 is to determine the location of the locomotive consist memberin the train, typically from the train location device in the leadlocomotive and from the knowledge of the number of cars that the consistmember is removed from the lead locomotive. If there is only onelocomotive, this step is trivial. In a long train where consist membersmay be at various locations, this step is included since consist memberscan be located in different operating zones. The next step 3205 is tolook ahead to project energy, emissions, noise and power requirements ofthe lead locomotive and all consist members for each section or zone ofthe train's up and coming route. In step 3206, the requirement foradditional engines currently deactivated is established from the dataacquired from step 3205. If additional engines are required, then thenumber of currently deactivated engines that must be activated isdetermined in step 3207. This engine activation step is described morefully in FIG. 17. The engine activation procedure is implemented in step1105 and the cycle then continues 3208. The cycle then continues 3209.As noted above, the locomotive operating mode is commonly set by thelocomotive's engineer. These are (1) a notch 1 to 8 power setting 3210,(2) an idle setting 3211, or (3) a dynamic braking setting 3212. Foreach of three power modes, it is possible that one or more engines maybe deactivated.

Deactivation means idling an engine so that it does not provide power tothe DC bus, or shutting off the engine. The deactivation of engines iscontrolled in step 3213. Step 3214 returns to the beginning of the maincontrol cycle.

FIG. 33 is a schematic of a preferred embodiment of multi-enginevoltage-based control feedback system with multiple engines in series.This schematic shows five engines 3301, each connected by mechanicalshafts 3302 to corresponding alternators 3303. Rectifiers 3304 areelectrically connected to the outputs of alternators 3303 to provide DCpower to a common DC bus 3305. In this embodiment, the output of the DCbus 3305 provides power to four traction motors 3306, where a singleload control apparatus 3307 controls the flow of power to all thetraction motors 3306. The load controlled traction motors are shownconnected in parallel with the load control apparatus 3307. Theelectrical outputs of the engine systems are connected in series withthe DC bus 3305. This figure illustrates a preferred engine balancingcontrol feedback loop. An input command 3310 (for example a selectedpower level) is issued to a controller 3311.

The output voltages from each engine system are measured by voltagesensors 3312 which are monitored by the controller 3311. The controller3311 then uses the measured voltages in a control feedback loop tomodify each engine's alternator 3303 excitation current (or alternatorvoltage boost if available) to bring each engine's power contributioninto balance with its pro rata portion of the total power to the DC bus.The control feedback loop is typically one of a number of well-knownproportional integral differential (“PID”) control algorithms. Thedotted lines 3320 represent voltage feedback control circuit connectionswhile the solid lines 3321 represent power distribution circuitconnections.

FIG. 34 is a schematic of an alternate multi-engine voltage-basedcontrol feedback system with multiple engines in series. This schematicshows five engines 3401, each connected by mechanical shafts 3402 tocorresponding alternators 3403. Rectifiers 3404 are electricallyconnected to the outputs of alternators 3403 to provide DC power to acommon DC bus 3405. In this embodiment, the output of the DC bus 3405provides power to four traction motors 3406, each shown with loadcontrol apparatuses 3407. The electrical outputs of the engine systemsare connected in series with the DC bus 3405. The load controlledtraction motors are also shown connected in parallel with the DC bus3405. This figure illustrates a less preferred engine balancing controlfeedback loop. An input command 3410 (for example a selected powerlevel) is issued to a controller 3411. The output voltages from eachengine system are measured by voltage sensors 3412 which are monitoredby the controller 3411. The controller 3411 then uses the measuredvoltages in a control feedback loop to modify each engine's 3401 speedto bring each engine's power contribution into balance with its pro rataportion of the total power to the DC bus. The control feedback loop istypically one of a number of well-known proportional integraldifferential (“PID”) control algorithms. The dotted lines 3420 representvoltage feedback control circuit connections while the solid lines 3421represent power distribution circuit connections. This feedback controlconfiguration is less preferable because (1) it is preferred to maintainthe engine speed and power output at its optimum operating mode setpoint and (2) the mechanical inertia of changing engine speeds tends tomake the feedback less responsive.

As can be appreciated, it is possible to use the measured enginesystem's output voltage to adjust or modify a combination of enginespeed, engine alternator excitation current and, if available,alternator voltage boost to balance the power outputs of all the enginesto the DC bus.

FIG. 35 is a schematic block diagram of a propulsion system for amulti-engine locomotive with multiple engines in parallel and a hybridauxiliary power system. In this configuration, three engines 3501 areused. Each engine 3501 drives a flywheel starter alternator which iscomprised of typically a smaller alternator 3503 which feeds power to anauxiliary power system DC bus and a typically larger alternator 3506which feeds power to a main propulsion DC bus. Alternators 3503 and 3506are driven by the output shaft of engine 3501 shown as shafts 3502 and3504. The main propulsion DC bus represented by bus bars 3510 and 3511receives DC power from rectifier circuits 3507.

In this example, the three engine systems are connected in parallel toboth the main propulsion DC bus and the auxiliary DC bus. The mainpropulsion DC bus is shown here driving a four traction motor propulsionsystem 3521, each of which is comprised of an electrical energyconverter and a motor. Also shown connected to the DC bus is a dynamicbraking resistive grid 3522. The auxiliary power system DC busrepresented by bus bars 3530 and 3531 receives DC power from rectifiercircuits 3505 and are shown here providing power to an energy storagesystem 3542 (which may be a battery pack, a capacitor bank or a flywheelenergy storage system for example) and an auxiliary power system 3541.As can be seen, the main propulsion DC bus can be operated at adifferent voltage and power level (typically higher) than the auxiliarypower system DC bus (typically lower). The auxiliary power system DC bussystem can be operated from the energy storage system alone such as forexample when the locomotive is parked and requires lighting, heating orair-conditioning for example. The energy storage system can be rechargedby plugging into an external power source or from the engines 3501 whilethe engines are idling or providing power to the main propulsion DC bus.

A conventional battery operated starter motor can be used to start anengine. Alternately, the voltage from the auxiliary DC bus, drawn fromthe energy storage device 3543, can be used with, for example, aninduction alternator to provide electrical power to start one or more ofthe engines 3501. This method of starting engines is known and is usedto provide high starting power without the need of a separate startermotor. A prelubrication pump can also be operated directly from theauxiliary DC bus or from an auxiliary power supply to lubricate a dieselengine just prior to starting it so as to extend its operationallifetime. While the above engine start-up procedures are well-known,they can be applied more readily utilizing the voltage control and DCbus architecture of the present invention.

As can be appreciated, the engine systems can be connected in eitherparallel or series to the main propulsion and auxiliary DC buses.

FIG. 36 is a schematic circuit diagram for a multi-engine locomotivewith multiple engines in parallel and a hybrid auxiliary power system.In this configuration, three engines systems 3601 are used. Each enginedrives a flywheel starter alternator which is comprised of a typicallysmaller alternator 3604 which feeds power to an auxiliary power systemDC bus via an induction alternator and converter system 3605; and atypically larger alternator 3602 which feeds power to a main propulsionDC bus via diode rectifier system 3603. The main propulsion DC busrepresented by bus bars 3610 and 3611 receives DC power from rectifiercircuits 3603 and are shown here driving four traction motor systems3621, each of which shown here, for example, as series wound DC motorswith field coil reversers and chopper controlled freewheeling circuits.Also shown connected to the DC bus is a dynamic braking resistive grid3622.

Engine systems 3604 are shown with induction alternator and convertersystems 3605. The alternator and converter systems 3605 allow energy andpower to flow to or from the auxiliary power DC bus. The battery pack3641 may be used to provide power for starting one or more engines 3604by any of a number of well-known methods. As can be appreciated, theenergy storage system 3641 can also be a capacitor bank or a flywheelstorage system. A similar electrical architecture for a multi-enginelocomotive was disclosed previously in U.S. patent application Ser. No.11/200,881 filed Aug. 19, 2005 entitled “Locomotive Power TrainArchitecture” and in U.S. Provisional patent application entitled“Marine Power Train Architecture” by Donnelly and Watson 25 filed Oct.24, 2006.

The auxiliary power system DC bus represented by bus bars 3630 and 3631receives DC power from alternator and converter systems 3605 and areshown here providing power to an energy storage system 3641 and itsoptional voltage buck/boost circuit 3642; and an auxiliary power system3643 and its optional voltage boost circuit 3644. As can be seen, themain propulsion DC bus can be operated at a different voltage and powerlevel (typically higher) than the auxiliary power system DC bus(typically lower). As described previously, the auxiliary power systemDC bus system can be operated from the energy storage system alone.

FIG. 37 is a schematic block diagram of an alternate propulsion systemfor a multi-engine locomotive with multiple engines in parallel and ahybrid auxiliary power system and is similar to the configuration shownin FIG. 35 except that the main propulsion system is driven by amechanical transmission rather than by an electrical transmission. Inthis configuration, three engines 3701 are used. Each engine 3701 drivesa flywheel starter alternator which is comprised of typically analternator 3705 driven by the engine output shaft 3702 which feeds powerto an auxiliary power system DC bus. Engine output shaft 3704 isconnected to a mechanical transmission 3706 and is shown here drivingfour traction motor propulsion systems 3707.

The transmission 3706 may be a synchronous transmission which wouldrequire the engines 3701 to be operated synchronously or thetransmission 3706 may be comprised of differential elements which wouldallow the engines 3701 to be operated asynchronously. The auxiliarypower system DC bus represented by bus bars 3710 and 3711 receives DCpower from alternator and converter systems 3705 and are shown hereproviding power to an energy storage system 3722 and an auxiliary powersystem 3721.

The auxiliary power system DC bus system can be operated from the energystorage system alone such as for example when the locomotive is parkedand requires lighting, heating or air-conditioning for example. Theenergy storage system can be recharged by plugging into an externalpower source or from the engines 3701 when idling or providing power tothe main propulsion DC bus.

Engine systems 3701 are shown with induction alternator and convertersystems 3705. The alternator and converter systems 3705 allow energy andpower to flow to or from the auxiliary power DC bus. The energy storagesystem 3722 may be used to provide power for starting one or moreengines 3701 by any of a number of well-known methods. As can beappreciated, the energy storage system 3722 can be a battery pack,capacitor bank or a flywheel energy storage system.

FIG. 38 is a schematic block diagram of yet another alternate propulsionsystem for a multi-engine locomotive with multiple engines in series anda hybrid auxiliary power system. In this configuration, three engines3801 are used and are shown connected in series. A principal advantageof this configuration is that the traction motor voltage can becontrolled by a) the number of engines providing power to the mainpropulsion bus; b) the engine speeds; and c) the alternator excitations.This eliminates the need for electrical energy converters connecting thetraction motors to the main propulsion DC bus. Each engine 3801 drives aflywheel starter alternator which is comprised of typically a smalleralternator 3803 which feeds power to an auxiliary power system DC busand a typically larger alternator 3806 which feeds power to a mainpropulsion DC bus. Alternators 3803 and 3806 are driven by the outputshaft of engine 3801 shown as shafts 3802 and 3804. The main propulsionDC bus represented by bus bars 3810 and 3811 receives DC power fromrectifier circuits 3807. In this example, the three engine systems areconnected in series to the main propulsion DC bus and in parallel to theauxiliary DC bus. The main propulsion DC bus is shown here driving afour traction motor propulsion system 3820, each of which is comprisedof only an AC or DC traction motor 3821. Also shown connected to the DCbus is a dynamic braking resistive grid 3822 and its on/off switch 3823.The auxiliary power system DC bus represented by bus bars 3830 and 3831receives DC power from rectifier circuits 3805 and are shown hereproviding power to an energy storage system 3842 (which may be a batterypack, a capacitor bank or a flywheel energy storage system for example)and an auxiliary power system 3841. As can be seen, the main propulsionDC bus can be operated at a different voltage and power level (typicallyhigher) than the auxiliary power system DC bus (typically lower). Theauxiliary power system DC bus system can be operated from the energystorage system alone such as for example when the locomotive is parkedand requires lighting, heating or air-conditioning for example. Theenergy storage system can be recharged by plugging into an externalpower source or from the engines 3801 while the engines are idling orproviding power to the main propulsion DC bus.

A conventional battery operated starter motor can be used to start anengine. Alternately, the voltage from the auxiliary DC bus, drawn fromthe energy storage device 3843, can be used with, for example, aninduction alternator to provide electrical power to start one or more ofthe engines 3801. This method of starting engines is known and is usedto provide high starting power without the need of a separate startermotor. A prelubrication pump can also be operated directly from theauxiliary DC bus or from an auxiliary power supply to lubricate a dieselengine just prior to starting it so as to extend its operationallifetime. While the above engine start-up procedures are well-known,they can be applied more readily utilizing the voltage control and DCbus architecture of the present invention.

FIG. 39 is an example of total DC bus input amperes versus bus volts fora three engine locomotive where the engine systems are connectedelectrically in series. The output amps 3902 typically range from 0 toabout 6,000 amps and the output volts 3901 typically range from 0 toabout 1,400 volts. Curve 3910 represents an amp-volt curve for a firstconstant power level, say 500 kW. Curve 3920 represents an amp-voltcurve for a second constant power level, say 1,000 kW and curve 3930represents an amp-volt curve for a third constant power level, say 1,500kW. Region 3940 which may be, for example, above about 4,400 ampsrepresents a region where a continuous current can be sustained for onlya short time, for example about 5 minutes. For longer operating times,the windings in the engine alternators that are providing power to theDC bus can become too hot as a result of I2R heating in the windings.Continuous operation of 1, 2 or 3 engine systems can be permitted belowthis approximate current limit. The graph is further divided into threevoltage regions 3951, 3952 and 3953 which are defined typically bymagnetic saturation of the stator core of the engine alternators. Forexample, the power for curve 3910 can be provided by a single enginesystem for output voltages in region 3951 (the power in region 3951 canalso be provided by two or three engine systems in this example). Inregion 3952 and 3953, the stator core of the alternator for a singleengine system will be magnetically saturated and so the power must beprovided by more than one engine system to avoid this condition. Atleast two engine systems are required to provide the power of curve 3910in region 3952 and all three engine systems are required to provide thepower of curve 3910 in region 3953. Typically the power supplied by eachengine system is pro-rated on the maximum engine power rating of eachengine system. As can be appreciated, the engine systems may be operatedto supply different amounts of power than their pro-rata share as longas no engine system is operated so as to magnetically saturate itsalternator stator core.

As another example, the power for curve 3920 must be provided by atleast two engine systems for output voltages in region 3951 and 3952. Inregion 3953, the alternator stator cores of the engine systems maybecome magnetically saturated and so the power must be provided by allthree engine systems to avoid this condition. Typically the powersupplied by each engine system is pro-rated on the maximum engine powerrating of each engine. As can be appreciated, the engine systems may beoperated to supply different amounts of power than their pro-rata shareas long as no engine system is operated so as to magnetically saturateits alternator stator core.

As yet another example, the power for curve 3930 must be provided by atall three engine systems for output voltages in region 3951, 3952 and3953 to avoid magnetically saturating the alternator stator cores.Typically the power supplied by each engine system is pro-rated on themaximum engine power rating of each engine. As can be appreciated, theengine system may be operated to supply different amounts of power thantheir prorate share as long as no engine system is operated so as tomagnetically saturate its alternator stator core.

FIG. 40 is an example of total locomotive tractive effort versuslocomotive speed for a three engine locomotive where the engine systemsare connected electrically in series. In this example, the totallocomotive tractive effort 4002 typically ranges from 0 to about 90,000lbs and the locomotive speed 4001 typically ranges from 0 to 70 mph.

Curve 4010 represents a tractive effort versus speed curve for a firstconstant power level, say 500 kW. Curve 4020 represents a tractiveeffort versus speed curve for a second constant power level, say 1,000kW and curve 4030 represents a tractive effort versus speed curve for athird constant power level, say 1,500 kW. When a constant power curve issmooth (for example curve 4010), this represents a single engine systemoperating. When a constant power curve has small normal crossing lines(for example curve 4020), this represents two engine systems operating.When a constant power curve has small crosses (for example curve 4030),this represents three engine systems operating. Curve 4010 illustratesthe tractive effort for a single engine operating until a speed isreached where the tractive effort from the single engine drops rapidlyas indicated by the portion of the curve 4011. This is a result ofalternator voltage limitation caused by magnetic saturation of thestator core. If a second engine system is operated to add power to theDC bus, then the tractive effort follows curve 4012 to a higherlocomotive speed before the tractive effort from the two engines dropsrapidly as a result of the aforementioned alternator voltage limitation.If a third engine is brought on line, then the tractive effort followscurve 4013 to an even higher locomotive speed before the tractive effortfrom the three engines drops rapidly.

Curve 4020 illustrates the tractive effort for two engines operatinguntil a speed is reached where the tractive effort from the two enginesdrops rapidly as indicated by the portion of the curve 4022. If a thirdengine system is brought on-line to add power to the DC bus, then thetractive effort follows curve 4023 to a higher locomotive speed beforethe tractive effort from the three engines drops rapidly.

Curve 4030 illustrates the tractive effort for all three enginesoperating at maximum power. This mode provides the maximum tractiveeffort at high speeds that can be developed by a three engine locomotivewhere the engine systems are connected electrically in series.

A number of variations and modifications of the invention can be used.As will be appreciated, it would be possible to provide for somefeatures of the invention without providing others. For example, in onealternative embodiment, the various inventive features may be applied tolarge trucks which could utilize multiple engines coupled to the drivingwheels by an electric transmission. This would allow, for example, atruck hauling multiple trailers to use the main truck engine for levelor downhill travel but add engine power when hauling uphill byactivating additional engines installed on each trailer being hauled bythe truck cab.

The present invention, in various embodiments, includes components,methods, processes, systems and/or apparatus substantially as depictedand described herein, including various embodiments, sub-combinations,and subsets thereof. Those of skill in the art will understand how tomake and use the present invention after understanding the presentdisclosure. The present invention, in various embodiments, includesproviding devices and processes in the absence of items not depictedand/or described herein or in various embodiments hereof, including inthe absence of such items as may have been used in previous devices orprocesses, for example for improving performance, achieving ease and/orreducing cost of implementation. The foregoing discussion of theinvention has been presented for purposes of illustration anddescription. The foregoing is not intended to limit the invention to theform or forms disclosed herein. In the foregoing Detailed Descriptionfor example, various features of the invention are grouped together inone or more embodiments for the purpose of streamlining the disclosure.This method of disclosure is not to be interpreted as reflecting anintention that the claimed invention requires more features than areexpressly recited in each claim. Rather, as the following claimsreflect, inventive aspects lie in less than all features of a singleforegoing disclosed embodiment. Thus, the following claims are herebyincorporated into this Detailed Description, with each claim standing onits own as a separate preferred embodiment of the invention. Moreoverthough the description of the invention has included description of oneor more embodiments and certain variations and modifications, othervariations and modifications are within the scope of the invention,e.g., as may be within the skill and knowledge of those in the art,after understanding the present disclosure. It is intended to obtainrights which include alternative embodiments to the extent permitted,including alternate, interchangeable and/or equivalent structures,functions, ranges or steps to those claimed, whether or not suchalternate, interchangeable and/or equivalent structures, functions,ranges or steps are disclosed herein, and without intending to publiclydedicate any patentable subject matter.

TABLE 1 Single Engine Notch Setting Engine RPMs Total BHP Low Idle 60013 High Idle 750 19 1 750 32 2 800 71 3 916 148 4 1,078 173 5 1,271 2686 1,566 383 7 1,634 519 8 1,800 630

TABLE 2 Fixed Engine Selection Number of Notch setting Engines EngineRPMs Total BHP Low Idle 1 600 12 High Idle 1 750 18 1 1 1,000 150 2 11,500 450 3 2 1,500 900 4 2 1,650 1,080 5 3 1,650 1,620 6 4 1,700 2,2807 5 1,800 3,150 8 6 1,800 3,780

TABLE 3 Last Engine Variable Notch Number of Engine RPM Last settingengines RPMs Engine On Total BHP Low Idle 1 600 13 High Idle 1 750 19 11 1,100 210 2 1 1,450 420 3 2 1,800 1,000 780 4 2 1,800 1,450 1,050 5 31,800 1,550 1,620 6 4 1,800 1,350 2,370 7 5 1,800 1,450 3,120 8 6 1,8001,800 3,780

TABLE 4 Selection Determined by Load Number of Engine Notch settingengines RPMs Total BHP Low Idle 1 600 13 High Idle 1 750 19 1 1 1,071193 2 1 1,458 425 3 3 1,244 889 4 3 1,326 1,038 5 4 1,421 1,611 6 61,388 2,297 7 6 1,615 3,113 8 6 1,800 3,780

TABLE 5 Fixed Number of Engines Number of Engine Notch setting enginesRPMs Total BHP Low Idle 2 600 25 High Idle 2 750 38 1 2 804 64 2 2 868142 3 2 997 296 4 2 1,038 346 5 2 1,197 537 6 2 1,388 766 7 2 1,6151,038 8 2 1,800 1,260

TABLE 6 Maximum Fuel Economy Number of Engine Notch setting engines RPMsTotal BHP Low Idle 1 600 204 High Idle 1 600 204 1 1 600 204 2 1 1,400492 3 2 1,400 984 4 2 1,500 1,056 5 3 1,550 1,638 6 4 1,600 2,256 7 51,700 3,000 8 6 1,750 3,708

TABLE 7 Minimum Emissions Number of Notch setting engines Engine RPMsTotal BHP Low Idle 1 600 204 High Idle 1 600 204 1 1 600 204 2 1 1,400492 3 2 1,400 984 4 2 1,550 1,092 5 3 1,550 1,638 6 4 1,650 2,328 7 51,900 3,150 8 6 1,900 3,780

TABLE 8 Hybrid Configuration

1. A method of controlling a desired total system output power from alocomotive comprising a plurality of power sources, the plurality ofpower sources outputting DC electrical power in parallel to a common DCbus, and said vehicle also comprising a variable power control having aplurality of power settings, said method comprising the steps of: a)selecting a number of power sources to be used according to a scheduleto provide power in parallel to the DC common bus; b) activating thepower sources according to said schedule; c) setting a desired range ofa parameter indicative of power available on the DC common bus from atleast one of voltage or current on the DC common bus; d) measuring asignal corresponding to the parameter indicative of power available onthe DC common bus from at least one of voltage or current on the DCcommon bus; e) for each of the plurality of power sources, measuring asignal indicative of a power source operational parameter from said eachof the plurality of power sources; f) determining an output power foreach of the plurality of power sources, based on the measurement of thesignal indicative of the power source operational parameter from saideach of the plurality of power sources and the signal corresponding tothe parameter indicative of at least one of voltage or current on the DCcommon bus; and g) if the output power of one of the plurality of powersources is different from a target output power, adjusting a powersource control parameter of said one of the plurality of power sourcesto correct the difference.
 2. The method according to claim 1, whereinthe power source operational parameter comprises at least one ofcurrent, voltage, torque, speed and fuel injection rate.
 3. The methodaccording to claim 1, wherein the parameter indicative of the poweravailable on the DC common bus is the DC common bus voltage, and thesignal indicative of the power source operational parameter is at leastone of current, voltage, torque, speed and fuel injection rate from saideach of the plurality of power sources.
 4. The method according to claim1, wherein all selected power sources in step a) operate at a same powerlevel.
 5. The method according to claim 1, wherein all selected powersources but one in step a) operate at a same power level, said one powersource operating at a different power level and enabling the allselected power sources but one to optimize an operating parameter. 6.The method of claim 5, wherein said operating parameter is selected fromthe group consisting of (i) fuel efficiency; (ii) low emissions; (iii)noise level; (iv) power; (v) tractive effort; (vi) engine lifetime,(vii) location of the vehicle and (viii) any combination thereof.
 7. Themethod according to claim 1, wherein each power setting corresponds to apower level which is obtained by adding another power source as soon asthe currently operating power sources reach a selected percentage oftheir rated power.
 8. The method according to claim 1, wherein anoperator of the vehicle manually selects at least one of the number ofpower sources to be used according to the schedule and an operatingparameter of one of the number of power sources to be used according tothe schedule, said operating parameter being selected from the groupconsisting of (i) fuel efficiency; (ii) low emissions; (iii) noiselevel; (iv) power; (v) tractive effort; (vi) engine lifetime, (vii)location of the vehicle, (viii) maximum engine output power, (ix) enginespeed and (x) any combination thereof.
 9. The method according to claim5, wherein said number of power sources to be used and the power andengine speed setting for each power source are selected in order toobtain a desired fuel efficiency for that power setting and aredetermined using a controller programmed to use fuel consumption mapsfor each power source.
 10. The method according to claim 5, wherein saidnumber of power sources to be used and the power and engine speedsetting for each power source in order to obtain the desired emissionsfor that power setting are determined using a controller programmed touse an emissions map for each power source.
 11. The method according toclaim 1, wherein said plurality of power sources comprise a plurality ofprime movers and one or more energy storage systems.
 12. The methodaccording to claim 1, wherein said variable power control having aplurality of power settings comprises one or more idle settings and aplurality of power notch settings.
 13. The method according to claim 1,wherein step a) comprises the steps of: i) determining a specifiedoutput power for a selected notch setting and vehicle speed; ii)selecting an optimum power source operating mode; iii) selecting anumber of power sources required to provide the specified output powerfor the selected notch setting and vehicle speed; iv) selecting specificpower sources to provide the specified output power for the selectednotch setting and vehicle speed; v) verifying whether any of theselected specific power sources need to be derated; vi) if a powersource from any of the selected specific power sources needs to bederated, derating said power source needing derating and returning tostep iii); and vii) if a power source from the plurality of powersources is not required to provide the specified output power for theselected notch setting and vehicle speed, deactivating said non-requiredpower source.
 14. The method according to claim 13, wherein the vehicleis operating in dynamic braking mode and further comprising, prior tostep a), the steps of: aa) selecting a dynamic braking power level; bb)determining if dynamic braking available power is sufficient forproviding the desired total system output power; cc) if the dynamicbraking available power is sufficient for providing the desired totalsystem output power, performing step g) wherein the desired total systemoutput power comprises output power from dynamic braking; and dd) if thedynamic braking available power is not sufficient for providing thedesired total system output power, performing step a) wherein thedesired total system output power comprises output power from dynamicbraking and output power from the plurality of power sources.
 15. Themethod according to claim 1, further comprising a step of deactivating aselected one of the plurality of power sources, said deactivating stepcomprising the steps of: I) selecting between an idle mode and ashutdown mode; II) if the idle mode is selected, performing the stepsof: A. selecting between a high idle power level and a low idle powerlevel; B. setting an excitation current for the selected deactivatingpower source such that an output voltage of the selected deactivatingpower source is below a DC common bus voltage; C. selecting an optimumoperating mode for the selected deactivating power source; and D.adjusting the excitation current for the selected deactivating powersource such that the output voltage of the selected deactivating powersource is below a DC common bus voltage and the selected deactivatingpower source achieves said optimum operating mode; and III) if theshutdown mode is selected, performing the steps of: E. from look-aheaddata, determining if the power source can be turned off; F. if a timerequired to shutdown the power source is below a threshold, performingsteps II) A through II) D; and G. if the time required to shutdown thepower source is above the threshold, turning off the engine.
 16. Themethod according to claim 1, wherein step b) comprises the steps of: I)if the power sources are off, preheating the power sources; II) turningon lubricating oil flow; III) starting the power sources; IV) selectingbetween a high idle power level and a low idle power level; V) settingan excitation current for the selected activating power source such thatan output voltage of the selected activating power source is below a DCcommon bus voltage VI) selecting an optimum operating mode for theselected activating power source; and VII) adjusting the excitationcurrent for the selected activating power source such that the outputvoltage of the selected deactivating power source is below a DC commonbus voltage and the selected activating power source achieves saidoptimum operating mode.
 17. A system for controlling a desired totalsystem output power from a locomotive comprising a plurality of powersources, the plurality of power sources outputting DC electrical powerin parallel to a common DC bus, and said vehicle also comprising avariable power control having a plurality of power settings, the controlsystem comprising: selecting means for selecting a number of powersources to be used according to a schedule to provide power to the DCcommon bus; activating means for activating the power sources accordingto said schedule; setting means for setting a desired range of aparameter indicative of power available on the DC common bus from atleast one of voltage or current on the DC common bus; first measuringmeans for measuring a signal corresponding to the parameter indicativeof power available on the DC common bus from at least one of voltage orcurrent on the DC common bus; second measuring means, for each of theplurality of power sources, for measuring a signal indicative of a powersource operational parameter from said each of the plurality of powersources; determining means for determining an output power for each ofthe plurality of power sources, based on the measurement of the signalindicative of the power source operational parameter from said each ofthe plurality of power sources and the signal corresponding to theparameter indicative of at least one of voltage or current on the DCcommon bus; and adjusting means for adjusting a power source controlparameter of said one of the plurality of power sources to correct adifference between the output power of one of the plurality of powersources and a target output power.
 18. The system according to claim 17,wherein the power source operational parameter comprises at least one ofcurrent, voltage, torque, speed and fuel injection rate.
 19. The systemaccording to claim 17, wherein the parameter indicative of the poweravailable on the DC common bus is the DC common bus voltage, and thesignal indicative of the power source operational parameter is at leastone of current, voltage, torque, speed and fuel injection rate from saideach of the plurality of power sources.
 20. The system according toclaim 19, wherein the system further comprises an energy storage systemand an auxiliary power system connected to the DC common bus and whereineach of the plurality of power sources comprises an output shaftconnected to a mechanical transmission driving a plurality of tractionmotor propulsion systems.